code: def processed_file(self, new_text, filename, old_text=None, write=False,
                         encoding=None):
          
          self.files.append(filename)
          if old_text is None:
              old_text = self._read_python_source(filename)[0]
              if old_text is None:
                  return
          equal = old_text == new_text
          self.print_output(old_text, new_text, filename, equal)
          if equal:
              self.log_debug("No changes to %s", filename)
              if not self.write_unchanged_files:
                  return
          if write:
              self.write_file(new_text, filename, old_text, encoding)
          else:
              self.log_debug("Not writing changes to %s", filename)
docs: Called when a file has been refactored and there may be changes.