docs: def _write_line(self, line=None):
          """
          Appends a line of code to the generated code and adjust the indent level of the generated code.
  
          :param line: The line of code (with out LF) that must be appended.
          """
          if line is None:
              self._write("\n")
              if self.__indent_level > 1:
                  self.__indent_level -= 1
          elif line == '':
              self._write("\n")
          else:
              line = (' ' * 4 * self.__indent_level) + line
              if line[-1:] == ':':
                  self.__indent_level += 1
              self._write(line + "\n")