sub looks_like_number {
  local $_ = shift;

  # checks from perlfaq4
  return $] < 5.009002 unless defined;
  return 1 if (/^[+-]?\d+$/); # is a +/- integer
  return 1 if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/); 
      # a C float
  return 1 if ( $] >= 5.008 and /^(Inf(inity)?|NaN)$/i) 
                or ($] >= 5.006001 and /^Inf$/i );

  0;
}

##</code><code>##

  return $] < 5.009002 unless defined;