public static Supplier<Integer> Int(final int start, final int step) {
		return new Supplier<>() {
			private int _value = start;

			@Override
			public Integer get() {
				return next();
			}

			private int next() {
				final int next = _value;
				_value += step;
				return next;
			}
		};
	}
Return an integer factory which creates an integer sequence starting with
{@code start} an with the given {@code step}.

@param step the gap between the generated integers.
@return an integer factory.
jenetics/src/test/java/io/jenetics/util/factories.java