code: func (c *Converter) RegisterGeneratedConversionFunc(conversionFunc interface{}) error {
  	fv := reflect.ValueOf(conversionFunc)
  	ft := fv.Type()
  	if err := verifyConversionFunctionSignature(ft); err != nil {
  		return err
  	}
  	c.generatedConversionFuncs[typePair{ft.In(0).Elem(), ft.In(1).Elem()}] = fv
  	return nil
  }
docs: // Similar to RegisterConversionFunc, but registers conversion function that were
  // automatically generated.