code: def validate(self, body, signature):
          
          gen_signature = hmac.new(
              self.channel_secret,
              body.encode('utf-8'),
              hashlib.sha256
          ).digest()
  
          return compare_digest(
                  signature.encode('utf-8'), base64.b64encode(gen_signature)
          )
docs: Check signature.
  
          https://devdocs.line.me/en/#webhook-authentication
  
          :param str body: Request body (as text)
          :param str signature: X-Line-Signature value (as text)
          :rtype: bool
          :return: result