code: def resolve_identifiers(self, subject_context):
          
          session = subject_context.session
          identifiers = subject_context.resolve_identifiers(session)
  
          if (not identifiers):
              msg = ("No identity (identifier_collection) found in the "
                     "subject_context.  Looking for a remembered identity.")
              logger.debug(msg)
  
              identifiers = self.get_remembered_identity(subject_context)
  
              if identifiers:
                  msg = ("Found remembered IdentifierCollection.  Adding to the "
                         "context to be used for subject construction.")
                  logger.debug(msg)
  
                  subject_context.identifiers = identifiers
                  subject_context.remembered = True
  
              else:
                  msg = ("No remembered identity found.  Returning original "
                         "context.")
                  logger.debug(msg)
  
          return subject_context
docs: ensures that a subject_context has identifiers and if it doesn't will
          attempt to locate them using heuristics