parameters: (self, length=4)
return_statement: return code, code
docstring: 生成字符串验证码
  
          @length: 字符串验证码允许的长度, 默认为4
docstring_summary: 生成字符串验证码
docstring_tokens: 生成字符串验证码
function: def _generate_string(self, length=4):
          """ 生成字符串验证码
  
          @length: 字符串验证码允许的长度, 默认为4
          """
          random_chars = [_ENABLED_STRINGS[random.randrange(0, len(_ENABLED_STRINGS))] for i in range(length)]
          code = ''.join(random_chars)
          return code, code
function_tokens: def _generate_string ( self , length = 4 ) : random_chars = [ _ENABLED_STRINGS [ random . randrange ( 0 , len ( _ENABLED_STRINGS ) ) ] for i in range ( length ) ] code = '' . join ( random_chars ) return code , code