code: def t_KEYWORD_AS_TAG(self, t):
          r'[a-zA-Z]+'
          t.type = self.reserved.get(t.value, 'UNKNOWN_TAG')
          t.value = t.value.strip()
          return f t_KEYWORD_AS_TAG(self, t):
          r'[a-zA-Z]+'
          t.type = self.reserved.get(t.value, 'UNKNOWN_TAG')
          t.value = t.value.strip()
          return t
docs: r'[a-zA-Z]+