sub _numberlike {
  return 1, unless defined $_[0];

  # L<perlfunc> manpage notes that NaN != NaN, so we can verify that
  # numeric conversion function works properly along with the
  # comparison operator.
  no warnings;

  return 1 if ((!ref $_[0]) || blessed($_[0])) &&
    eval {
      ((0+$_[0]) == (0+$_[0])) && (($_[0] <=> $_[0])==0)
    };
  return;
}