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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def extend(validator, validators=(), version=None, type_checker=None):
 """ Create a new validator class by extending an existing one. Arguments: validator (jsonschema.IValidator):
 an existing validator class validators (collections.Mapping):
 a mapping of new validator callables to extend with, whose structure is as in `create`. .. note:: Any validator callables with the same name as an existing one will (silently) replace the old validator callable entirely, effectively overriding any validation done in the "parent" validator class. If you wish to instead extend the behavior of a parent's validator callable, delegate and call it directly in the new validator function by retrieving it using ``OldValidator.VALIDATORS["validator_name"]``. version (str):
 a version for the new validator class type_checker (jsonschema.TypeChecker):
 a type checker, used when applying the :validator:`type` validator. If unprovided, the type checker of the extended `jsonschema.IValidator` will be carried along.` Returns: a new `jsonschema.IValidator` class extending the one provided .. note:: Meta Schemas The new validator class will have its parent's meta schema. If you wish to change or extend the meta schema in the new validator class, modify ``META_SCHEMA`` directly on the returned class. Note that no implicit copying is done, so a copy should likely be made before modifying it, in order to not affect the old validator. """


    all_validators = dict(validator.VALIDATORS)
    all_validators.update(validators)

    if type_checker is None:
        type_checker = validator.TYPE_CHECKER
    elif validator._CREATED_WITH_DEFAULT_TYPES:
        raise TypeError(
            "Cannot extend a validator created with default_types "
            "with a type_checker. Update the validator to use a "
            "type_checker when created."
        )
    return create(
        meta_schema=validator.META_SCHEMA,
        validators=all_validators,
        version=version,
        type_checker=type_checker,
        id_of=validator.ID_OF,
    )