code: def set_file_name(self, doc, name):
          
          if self.has_package(doc):
              doc.package.files.append(file.File(name))
              # A file name marks the start of a new file instance.
              # The builder must be reset
              # FIXME: this state does not make sense
              self.reset_file_stat()
              return True
          else:
              raise OrderError('File::Name')
docs: Raises OrderError if no package defined.