code: def set_annotation_spdx_id(self, doc, spdx_id):
          
          if len(doc.annotations) != 0:
              if not self.annotation_spdx_id_set:
                  self.annotation_spdx_id_set = True
                  doc.annotations[-1].spdx_id = spdx_id
                  return True
              else:
                  raise CardinalityError('Annotation::SPDXREF')
          else:
              raise OrderError('Annotation::SPDXREF')
docs: Sets the annotation SPDX Identifier.
          Raises CardinalityError if already set. OrderError if no annotator
          defined before.