static <T> Error<T>
	of(final LossFunction<T> loss, final Complexity<T> complexity) {
		return of(loss, complexity, (lss, cpx) -> lss + lss*cpx);
	}
Creates an error function by combining the given {@code loss} function
and program {@code complexity}. The loss function and program complexity
is combined in the following way: {@code error = loss + loss*complexity}.
The complexity function penalizes programs which grow to big.

@param <T> the sample type
@param loss the loss function
@param complexity the program complexity measure
@return a new error function by combining the given loss and complexity
        function
@throws NullPointerException if one of the functions is {@code null}
jenetics.prog/src/main/java/io/jenetics/prog/regression/Error.java