SYNOPSIS
  use Xray::Scattering;
  Xray::Scattering->load('None');
  $fnot = Xray::Scattering->get_f($symb, $d);
DESCRIPTION
This module provides a fallback subclass for the Xray::Scattering methods. It provides all the methods of the real subclasses, but returns fallback values.METHODS
- "get_f"
 - Retruns 0.
 - "get_coefficients"
 - returns an array of 11 zeros.
 - "has"
 - Always returns the symbol itself.
 

