Django/docs/2.2.x/ modules/django/db/migrations/operations/models
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django.db.migrations.operations.models 源代码
from django.db import models
from django.db.migrations.operations.base import Operation
from django.db.migrations.state import ModelState
from django.db.models.options import normalize_together
from django.utils.functional import cached_property
from .fields import (
AddField, AlterField, FieldOperation, RemoveField, RenameField,
)
from .utils import ModelTuple, field_references_model
def _check_for_duplicates(arg_name, objs):
used_vals = set()
for val in objs:
if val in used_vals:
raise ValueError(
"Found duplicate value %s in CreateModel %s argument." % (val, arg_name)
)
used_vals.add(val)
class ModelOperation(Operation):
def __init__(self, name):
self.name = name
@cached_property
def name_lower(self):
return self.name.lower()
def references_model(self, name, app_label=None):
return name.lower() == self.name_lower
def reduce(self, operation, app_label=None):
return (
super().reduce(operation, app_label=app_label) or
not operation.references_model(self.name, app_label)
)
[文档]class CreateModel(ModelOperation):
"""Create a model's table."""
serialization_expand_args = ['fields', 'options', 'managers']
def __init__(self, name, fields, options=None, bases=None, managers=None):
self.fields = fields
self.options = options or {}
self.bases = bases or (models.Model,)
self.managers = managers or []
super().__init__(name)
# Sanity-check that there are no duplicated field names, bases, or
# manager names
_check_for_duplicates('fields', (name for name, _ in self.fields))
_check_for_duplicates('bases', (
base._meta.label_lower if hasattr(base, '_meta') else
base.lower() if isinstance(base, str) else base
for base in self.bases
))
_check_for_duplicates('managers', (name for name, _ in self.managers))
def deconstruct(self):
kwargs = {
'name': self.name,
'fields': self.fields,
}
if self.options:
kwargs['options'] = self.options
if self.bases and self.bases != (models.Model,):
kwargs['bases'] = self.bases
if self.managers and self.managers != [('objects', models.Manager())]:
kwargs['managers'] = self.managers
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.add_model(ModelState(
app_label,
self.name,
list(self.fields),
dict(self.options),
tuple(self.bases),
list(self.managers),
))
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.create_model(model)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.delete_model(model)
def describe(self):
return "Create %smodel %s" % ("proxy " if self.options.get("proxy", False) else "", self.name)
def references_model(self, name, app_label=None):
name_lower = name.lower()
if name_lower == self.name_lower:
return True
# Check we didn't inherit from the model
model_tuple = ModelTuple(app_label, name_lower)
for base in self.bases:
if (base is not models.Model and isinstance(base, (models.base.ModelBase, str)) and
ModelTuple.from_model(base) == model_tuple):
return True
# Check we have no FKs/M2Ms with it
for _name, field in self.fields:
if field_references_model(field, model_tuple):
return True
return False
def reduce(self, operation, app_label=None):
if (isinstance(operation, DeleteModel) and
self.name_lower == operation.name_lower and
not self.options.get("proxy", False)):
return []
elif isinstance(operation, RenameModel) and self.name_lower == operation.old_name_lower:
return [
CreateModel(
operation.new_name,
fields=self.fields,
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterModelOptions) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, **operation.options},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterTogetherOptionOperation) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, **{operation.option_name: operation.option_value}},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterOrderWithRespectTo) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, 'order_with_respect_to': operation.order_with_respect_to},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, FieldOperation) and self.name_lower == operation.model_name_lower:
if isinstance(operation, AddField):
return [
CreateModel(
self.name,
fields=self.fields + [(operation.name, operation.field)],
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterField):
return [
CreateModel(
self.name,
fields=[
(n, operation.field if n == operation.name else v)
for n, v in self.fields
],
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, RemoveField):
options = self.options.copy()
for option_name in ('unique_together', 'index_together'):
option = options.pop(option_name, None)
if option:
option = set(filter(bool, (
tuple(f for f in fields if f != operation.name_lower) for fields in option
)))
if option:
options[option_name] = option
order_with_respect_to = options.get('order_with_respect_to')
if order_with_respect_to == operation.name_lower:
del options['order_with_respect_to']
return [
CreateModel(
self.name,
fields=[
(n, v)
for n, v in self.fields
if n.lower() != operation.name_lower
],
options=options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, RenameField):
options = self.options.copy()
for option_name in ('unique_together', 'index_together'):
option = options.get(option_name)
if option:
options[option_name] = {
tuple(operation.new_name if f == operation.old_name else f for f in fields)
for fields in option
}
order_with_respect_to = options.get('order_with_respect_to')
if order_with_respect_to == operation.old_name:
options['order_with_respect_to'] = operation.new_name
return [
CreateModel(
self.name,
fields=[
(operation.new_name if n == operation.old_name else n, v)
for n, v in self.fields
],
options=options,
bases=self.bases,
managers=self.managers,
),
]
return super().reduce(operation, app_label=app_label)
[文档]class DeleteModel(ModelOperation):
"""Drop a model's table."""
def deconstruct(self):
kwargs = {
'name': self.name,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.remove_model(app_label, self.name_lower)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.delete_model(model)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.create_model(model)
def references_model(self, name, app_label=None):
# The deleted model could be referencing the specified model through
# related fields.
return True
def describe(self):
return "Delete model %s" % self.name
[文档]class RenameModel(ModelOperation):
"""Rename a model."""
def __init__(self, old_name, new_name):
self.old_name = old_name
self.new_name = new_name
super().__init__(old_name)
@cached_property
def old_name_lower(self):
return self.old_name.lower()
@cached_property
def new_name_lower(self):
return self.new_name.lower()
def deconstruct(self):
kwargs = {
'old_name': self.old_name,
'new_name': self.new_name,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
# Add a new model.
renamed_model = state.models[app_label, self.old_name_lower].clone()
renamed_model.name = self.new_name
state.models[app_label, self.new_name_lower] = renamed_model
# Repoint all fields pointing to the old model to the new one.
old_model_tuple = ModelTuple(app_label, self.old_name_lower)
new_remote_model = '%s.%s' % (app_label, self.new_name)
to_reload = []
for (model_app_label, model_name), model_state in state.models.items():
model_changed = False
for index, (name, field) in enumerate(model_state.fields):
changed_field = None
remote_field = field.remote_field
if remote_field:
remote_model_tuple = ModelTuple.from_model(
remote_field.model, model_app_label, model_name
)
if remote_model_tuple == old_model_tuple:
changed_field = field.clone()
changed_field.remote_field.model = new_remote_model
through_model = getattr(remote_field, 'through', None)
if through_model:
through_model_tuple = ModelTuple.from_model(
through_model, model_app_label, model_name
)
if through_model_tuple == old_model_tuple:
if changed_field is None:
changed_field = field.clone()
changed_field.remote_field.through = new_remote_model
if changed_field:
model_state.fields[index] = name, changed_field
model_changed = True
if model_changed:
to_reload.append((model_app_label, model_name))
# Reload models related to old model before removing the old model.
state.reload_models(to_reload, delay=True)
# Remove the old model.
state.remove_model(app_label, self.old_name_lower)
state.reload_model(app_label, self.new_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.new_name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.old_name)
# Move the main table
schema_editor.alter_db_table(
new_model,
old_model._meta.db_table,
new_model._meta.db_table,
)
# Alter the fields pointing to us
for related_object in old_model._meta.related_objects:
if related_object.related_model == old_model:
model = new_model
related_key = (app_label, self.new_name_lower)
else:
model = related_object.related_model
related_key = (
related_object.related_model._meta.app_label,
related_object.related_model._meta.model_name,
)
to_field = to_state.apps.get_model(
*related_key
)._meta.get_field(related_object.field.name)
schema_editor.alter_field(
model,
related_object.field,
to_field,
)
# Rename M2M fields whose name is based on this model's name.
fields = zip(old_model._meta.local_many_to_many, new_model._meta.local_many_to_many)
for (old_field, new_field) in fields:
# Skip self-referential fields as these are renamed above.
if new_field.model == new_field.related_model or not new_field.remote_field.through._meta.auto_created:
continue
# Rename the M2M table that's based on this model's name.
old_m2m_model = old_field.remote_field.through
new_m2m_model = new_field.remote_field.through
schema_editor.alter_db_table(
new_m2m_model,
old_m2m_model._meta.db_table,
new_m2m_model._meta.db_table,
)
# Rename the column in the M2M table that's based on this
# model's name.
schema_editor.alter_field(
new_m2m_model,
old_m2m_model._meta.get_field(old_model._meta.model_name),
new_m2m_model._meta.get_field(new_model._meta.model_name),
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
self.database_forwards(app_label, schema_editor, from_state, to_state)
self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
def references_model(self, name, app_label=None):
return (
name.lower() == self.old_name_lower or
name.lower() == self.new_name_lower
)
def describe(self):
return "Rename model %s to %s" % (self.old_name, self.new_name)
def reduce(self, operation, app_label=None):
if (isinstance(operation, RenameModel) and
self.new_name_lower == operation.old_name_lower):
return [
RenameModel(
self.old_name,
operation.new_name,
),
]
# Skip `ModelOperation.reduce` as we want to run `references_model`
# against self.new_name.
return (
super(ModelOperation, self).reduce(operation, app_label=app_label) or
not operation.references_model(self.new_name, app_label)
)
[文档]class AlterModelTable(ModelOperation):
"""Rename a model's table."""
def __init__(self, name, table):
self.table = table
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'table': self.table,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.models[app_label, self.name_lower].options["db_table"] = self.table
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.name)
schema_editor.alter_db_table(
new_model,
old_model._meta.db_table,
new_model._meta.db_table,
)
# Rename M2M fields whose name is based on this model's db_table
for (old_field, new_field) in zip(old_model._meta.local_many_to_many, new_model._meta.local_many_to_many):
if new_field.remote_field.through._meta.auto_created:
schema_editor.alter_db_table(
new_field.remote_field.through,
old_field.remote_field.through._meta.db_table,
new_field.remote_field.through._meta.db_table,
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
return self.database_forwards(app_label, schema_editor, from_state, to_state)
def describe(self):
return "Rename table for %s to %s" % (
self.name,
self.table if self.table is not None else "(default)"
)
def reduce(self, operation, app_label=None):
if isinstance(operation, (AlterModelTable, DeleteModel)) and self.name_lower == operation.name_lower:
return [operation]
return super().reduce(operation, app_label=app_label)
class ModelOptionOperation(ModelOperation):
def reduce(self, operation, app_label=None):
if isinstance(operation, (self.__class__, DeleteModel)) and self.name_lower == operation.name_lower:
return [operation]
return super().reduce(operation, app_label=app_label)
class AlterTogetherOptionOperation(ModelOptionOperation):
option_name = None
def __init__(self, name, option_value):
if option_value:
option_value = set(normalize_together(option_value))
setattr(self, self.option_name, option_value)
super().__init__(name)
@cached_property
def option_value(self):
return getattr(self, self.option_name)
def deconstruct(self):
kwargs = {
'name': self.name,
self.option_name: self.option_value,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.options[self.option_name] = self.option_value
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.name)
alter_together = getattr(schema_editor, 'alter_%s' % self.option_name)
alter_together(
new_model,
getattr(old_model._meta, self.option_name, set()),
getattr(new_model._meta, self.option_name, set()),
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
return self.database_forwards(app_label, schema_editor, from_state, to_state)
def references_field(self, model_name, name, app_label=None):
return (
self.references_model(model_name, app_label) and
(
not self.option_value or
any((name in fields) for fields in self.option_value)
)
)
def describe(self):
return "Alter %s for %s (%s constraint(s))" % (self.option_name, self.name, len(self.option_value or ''))
[文档]class AlterUniqueTogether(AlterTogetherOptionOperation):
"""
Change the value of unique_together to the target one.
Input value of unique_together must be a set of tuples.
"""
option_name = 'unique_together'
def __init__(self, name, unique_together):
super().__init__(name, unique_together)
[文档]class AlterIndexTogether(AlterTogetherOptionOperation):
"""
Change the value of index_together to the target one.
Input value of index_together must be a set of tuples.
"""
option_name = "index_together"
def __init__(self, name, index_together):
super().__init__(name, index_together)
[文档]class AlterOrderWithRespectTo(ModelOptionOperation):
"""Represent a change with the order_with_respect_to option."""
option_name = 'order_with_respect_to'
def __init__(self, name, order_with_respect_to):
self.order_with_respect_to = order_with_respect_to
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'order_with_respect_to': self.order_with_respect_to,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.options['order_with_respect_to'] = self.order_with_respect_to
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.name)
# Remove a field if we need to
if from_model._meta.order_with_respect_to and not to_model._meta.order_with_respect_to:
schema_editor.remove_field(from_model, from_model._meta.get_field("_order"))
# Add a field if we need to (altering the column is untouched as
# it's likely a rename)
elif to_model._meta.order_with_respect_to and not from_model._meta.order_with_respect_to:
field = to_model._meta.get_field("_order")
if not field.has_default():
field.default = 0
schema_editor.add_field(
from_model,
field,
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
self.database_forwards(app_label, schema_editor, from_state, to_state)
def references_field(self, model_name, name, app_label=None):
return (
self.references_model(model_name, app_label) and
(
self.order_with_respect_to is None or
name == self.order_with_respect_to
)
)
def describe(self):
return "Set order_with_respect_to on %s to %s" % (self.name, self.order_with_respect_to)
[文档]class AlterModelOptions(ModelOptionOperation):
"""
Set new model options that don't directly affect the database schema
(like verbose_name, permissions, ordering). Python code in migrations
may still need them.
"""
# Model options we want to compare and preserve in an AlterModelOptions op
ALTER_OPTION_KEYS = [
"base_manager_name",
"default_manager_name",
"default_related_name",
"get_latest_by",
"managed",
"ordering",
"permissions",
"default_permissions",
"select_on_save",
"verbose_name",
"verbose_name_plural",
]
def __init__(self, name, options):
self.options = options
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'options': self.options,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.options = {**model_state.options, **self.options}
for key in self.ALTER_OPTION_KEYS:
if key not in self.options:
model_state.options.pop(key, False)
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
pass
def database_backwards(self, app_label, schema_editor, from_state, to_state):
pass
def describe(self):
return "Change Meta options on %s" % self.name
[文档]class AlterModelManagers(ModelOptionOperation):
"""Alter the model's managers."""
serialization_expand_args = ['managers']
def __init__(self, name, managers):
self.managers = managers
super().__init__(name)
def deconstruct(self):
return (
self.__class__.__qualname__,
[self.name, self.managers],
{}
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.managers = list(self.managers)
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
pass
def database_backwards(self, app_label, schema_editor, from_state, to_state):
pass
def describe(self):
return "Change managers on %s" % self.name
class IndexOperation(Operation):
option_name = 'indexes'
@cached_property
def model_name_lower(self):
return self.model_name.lower()
[文档]class AddIndex(IndexOperation):
"""Add an index on a model."""
def __init__(self, model_name, index):
self.model_name = model_name
if not index.name:
raise ValueError(
"Indexes passed to AddIndex operations require a name "
"argument. %r doesn't have one." % index
)
self.index = index
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
model_state.options[self.option_name] = [*model_state.options[self.option_name], self.index.clone()]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.add_index(model, self.index)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.remove_index(model, self.index)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'index': self.index,
}
return (
self.__class__.__qualname__,
[],
kwargs,
)
def describe(self):
return 'Create index %s on field(s) %s of model %s' % (
self.index.name,
', '.join(self.index.fields),
self.model_name,
)
[文档]class RemoveIndex(IndexOperation):
"""Remove an index from a model."""
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
indexes = model_state.options[self.option_name]
model_state.options[self.option_name] = [idx for idx in indexes if idx.name != self.name]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
from_model_state = from_state.models[app_label, self.model_name_lower]
index = from_model_state.get_index_by_name(self.name)
schema_editor.remove_index(model, index)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
to_model_state = to_state.models[app_label, self.model_name_lower]
index = to_model_state.get_index_by_name(self.name)
schema_editor.add_index(model, index)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'name': self.name,
}
return (
self.__class__.__qualname__,
[],
kwargs,
)
def describe(self):
return 'Remove index %s from %s' % (self.name, self.model_name)
[文档]class AddConstraint(IndexOperation):
option_name = 'constraints'
def __init__(self, model_name, constraint):
self.model_name = model_name
self.constraint = constraint
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
model_state.options[self.option_name] = [*model_state.options[self.option_name], self.constraint]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.add_constraint(model, self.constraint)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.remove_constraint(model, self.constraint)
def deconstruct(self):
return self.__class__.__name__, [], {
'model_name': self.model_name,
'constraint': self.constraint,
}
def describe(self):
return 'Create constraint %s on model %s' % (self.constraint.name, self.model_name)
[文档]class RemoveConstraint(IndexOperation):
option_name = 'constraints'
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
constraints = model_state.options[self.option_name]
model_state.options[self.option_name] = [c for c in constraints if c.name != self.name]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
from_model_state = from_state.models[app_label, self.model_name_lower]
constraint = from_model_state.get_constraint_by_name(self.name)
schema_editor.remove_constraint(model, constraint)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
to_model_state = to_state.models[app_label, self.model_name_lower]
constraint = to_model_state.get_constraint_by_name(self.name)
schema_editor.add_constraint(model, constraint)
def deconstruct(self):
return self.__class__.__name__, [], {
'model_name': self.model_name,
'name': self.name,
}
def describe(self):
return 'Remove constraint %s from model %s' % (self.name, self.model_name)
