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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 _get_entity_ids(field_name, attrs):
 """Find the IDs for a one to many relationship. The server may return JSON data in the following forms for a :class:`nailgun.entity_fields.OneToManyField`:: 'user': [{'id': 1, …}, {'id': 42, …}] 'users': [{'id': 1, …}, {'id': 42, …}] 'user_ids': [1, 42] Search ``attrs`` for a one to many ``field_name`` and return its ID. :param field_name: A string. The name of a field. :param attrs: A dict. A JSON payload as returned from a server. :returns: An iterable of entity IDs. """

    field_name_ids = field_name + '_ids'
    plural_field_name = pluralize(field_name)
    if field_name_ids in attrs:
        return attrs[field_name_ids]
    elif field_name in attrs:
        return [entity['id'] for entity in attrs[field_name]]
    elif plural_field_name in attrs:
        return [entity['id'] for entity in attrs[plural_field_name]]
    else:
        raise MissingValueError(
            'Cannot find a value for the "{0}" field. Searched for keys named '
            '{1}, but available keys are {2}.'
            .format(
                field_name,
                (field_name_ids, field_name, plural_field_name),
                attrs.keys()
            )
        )