docs: def _certify_int_param(value, negative=True, required=False):
      """
      A private certifier (to `certifiable`) to certify integers from `certify_int`.
  
      :param int value:
          The value to certify is an integer.
      :param bool negative:
          If the value can be negative. Default=False.
      :param bool required:
          If the value is required. Default=False.
       :raises CertifierParamError:
          Value was not an integer (if required and non-None).
     """
      if value is None and not required:
          return
  
      if not isinstance(value, int):
          raise CertifierTypeError(
              message="expected integer, but value is of type {cls!r}".format(
                  cls=value.__class__.__name__),
              value=value,
              required=required,
  
          )
      if not negative and value < 0:
          raise CertifierValueError(
              message="expected positive integer, but value is negative")