Null-safe math operators

Gosu provides null-safe versions of common math operators.

For example, the standard operators for addition, subtraction, multiplication, division, and modulo are as follows: +, -, *, /, and %. If you use these standard operators and either side of the operator is null, Gosu throws a NullPointerException exception.

In contrast, the null-safe operators are the same symbols but with a question mark (?) character preceding it. In other words, the null-safe operators are: ?+, ?-, ?*, ?/, and ?%.