code: def t_MACROS(t):
      r'__[a-zA-Z]+__'
  
      if t.value in macros:
          t.type = t.value
          return t
  
      syntax_error(t.lexer.lineno, "unknown macro '%s'" % t.valuef t_MACROS(t):
      r'__[a-zA-Z]+__'
  
      if t.value in macros:
          t.type = t.value
          return t
  
      syntax_error(t.lexer.lineno, "unknown macro '%s'" % t.value)
docs: r'__[a-zA-Z]+__