code: def _id_of(schema):
      if schema is True or schema is False:
          return ""
      return schema.get("$id", "")
  
imports: from __future__ import division
  from warnings import warn
  import contextlib
  import json
  import numbers
  from six import add_metaclass
  from jsonschema import _legacy_validators, _types, _utils, _validators, exceptions
  from jsonschema.compat import Sequence, int_types, iteritems, lru_cache, str_types, unquote, urldefrag, urljoin, urlopen, urlsplit
  from jsonschema.exceptions import ErrorTree
label_desc: Use image node_id 4 for calling a global function with example usage: _id_of(schema) and returns: schema, str