code: def _validate(self, p):
          
          if self._is_operator(p):
              for operator_or_filter in (p[1] if p[0] != '!' else [p[1]]):
                  if p[0] == '^':
                      self._validate_xor_args(p)
                  self._validate(operator_or_filter)
          elif not self._is_value_filter(p) and not self._is_key_filter(p):
              raise ValueError('Not a valid operator or filter - {0}'.format(p))
docs: Recursively validates the pattern (p), ensuring it adheres to the proper key names and structure.