code: def needs_to_be_resolved(parent_obj, attr_name):
      
      if hasattr(get_model(parent_obj), "_tx_reference_resolver"):
          return get_model(parent_obj)._tx_reference_resolver. \
              has_unresolved_crossrefs(parent_obj, attr_name)
      else:
          return False
docs: This function determines, if a reference (CrossReference) needs to be
      resolved or not (while creating the model, while resolving references).
  
      Args:
          parent_obj: the object containing the attribute to be resolved.
          attr_name: the attribute identification object.
  
      Returns:
          True if the attribute needs to be resolved. Else False.
          In case of lists of references, this function return true if any of the
          references in the list needs to be resolved.
          Note: outside the model building process (from_file or from_str) this
          function always returns False.