code: def set_file_copyright(self, doc, text):
          
          if self.has_package(doc) and self.has_file(doc):
              if not self.file_copytext_set:
                  self.file_copytext_set = True
                  if validations.validate_file_cpyright(text):
                      if isinstance(text, string_types):
                          self.file(doc).copyright = str_from_text(text)
                      else:
                          self.file(doc).copyright = text  # None or NoAssert
                      return True
                  else:
                      raise SPDXValueError('File::CopyRight')
              else:
                  raise CardinalityError('File::CopyRight')
          else:
              raise OrderError('File::CopyRight')
docs: Raises OrderError if no package or file defined.
          Raises SPDXValueError if not free form text or NONE or NO_ASSERT.
          Raises CardinalityError if more than one.