parameters: (src, allow_char)
return_statement: return result
docstring: 根据具体的规则获取具体的字符
docstring_summary: 根据具体的规则获取具体的字符
docstring_tokens: 根据具体的规则获取具体的字符
function: def take(src, allow_char):
      """根据具体的规则获取具体的字符"""
      result = ''
      while src.current() in allow_char:
          result += src.pop()
      return result
function_tokens: def take ( src , allow_char ) : result = '' while src . current ( ) in allow_char : result += src . pop ( ) return result