code: def get_mds_key(self):
      assert self.is_http
      m = re.match(re.escape(MDS_URI_PREFIX) + r"(.*?)($|#)", self.uri)
      if m:
          return m.group(1)
      raise AssertionError(
          "Failed to extract mds key properly from '{}'".format(
              self.uri
          )
      )
  
imports: from __future__ import absolute_import
  import re
  import sys
  import copy
  import logging
  from .None import tools
  from datetime import date, datetime
  import enum
  import six
label_desc: Use image node_id 11 for calling the ExternalDataInfo obj's underlying member method code with example usage: obj.get_mds_key() and returns: m