code: def check_signature(self):
          
          if not self.signature:
              return True
          signature_value = request.headers.get(self.signature, None)
          if signature_value:
              validator = 'check_' + re.sub(r'[-]', '_', self.signature).lower()
              check_signature = getattr(signatures, validator)
              if check_signature(signature_value, request.data):
                  return True
          return False
docs: Check signature of signed request.