code: def t_IDENTIFIER(self, t):
          r'[a-zA-Z_][a-zA-Z0-9_]*'
          t.type = self.reserved_words.get(t.value, 'IDENTIFIER')
          return f t_IDENTIFIER(self, t):
          r'[a-zA-Z_][a-zA-Z0-9_]*'
          t.type = self.reserved_words.get(t.value, 'IDENTIFIER')
          return t
docs: r'[a-zA-Z_][a-zA-Z0-9_]*