code: def add_annotation_comment(self, doc, comment):
          
          if len(doc.annotations) != 0:
              if not self.annotation_comment_set:
                  self.annotation_comment_set = True
                  if validations.validate_annotation_comment(comment):
                      doc.annotations[-1].comment = str_from_text(comment)
                      return True
                  else:
                      raise SPDXValueError('AnnotationComment::Comment')
              else:
                  raise CardinalityError('AnnotationComment::Comment')
          else:
              raise OrderError('AnnotationComment::Comment')
docs: Sets the annotation comment. Raises CardinalityError if
          already set. OrderError if no annotator defined before.
          Raises SPDXValueError if comment is not free form text.