code: public WasDerivedFrom newWasDerivedFrom(QualifiedName id, 
                                              QualifiedName e2,
  					    QualifiedName e1) {
  	WasDerivedFrom res = of.createWasDerivedFrom();
  	res.setId(id);
  	res.setUsedEntity(e1);
  	res.setGeneratedEntity(e2);
  	return res;
      }
docs: A factory method to create an instance of a derivation {@link WasDerivedFrom}
  @param id an optional identifier for a derivation
  @param e2 the identifier  of the <a href="http://www.w3.org/TR/prov-dm/#derivation.generatedEntity">entity generated</a> by the derivation
  @param e1 the identifier  of the <a href="http://www.w3.org/TR/prov-dm/#derivation.usedEntity">entity used</a> by the derivation
  @return an instance of {@link WasDerivedFrom}