code: def set_pkg_license_comment(self, doc, text):
          
          self.assert_package_exists()
          if not self.package_license_comment_set:
              self.package_license_comment_set = True
              doc.package.license_comment = text
              return True
          else:
              raise CardinalityError('Package::LicenseComment')
docs: Sets the package's license comment.
          Raises OrderError if no package previously defined.
          Raises CardinalityError if already set.