code: public Bindings getBindings(String attribute) {
  	if (_bindings == null || attribute == null) return null;
  	return (Bindings)_bindings.get(canonicalize(attribute));
      }
docs: Returns the variable definitions associated wit the given
  attribute.
  
  @param attribute the attribute of the variable deinitions.
  @return the variable deinitions for the attribute.
  Null, if not found.