Add modulo math function

[rbong]

Hi, great library, I can't ever get enough callbacks!

I think this modulo function could be really useful. Take this elegant FizzBuzz implementation for example.

var modulo = require('callbaxx').modulo;
var isTrue = require('callbaxx').isTrue;

function fizzbuzz(cb) {
  for (var i = 1; i <= 100; i++) {
    modulo(i, 15, function(err, res) {
      isTrue(res === 0, function(err, res) {
        if (res) {
          console.log('FizzBuzz');
        } else {
          modulo(i, 3, function(err, res) {
            isTrue(res === 0, function(err, res) {
              if (res) {
                console.log('Fizz');
              } else {
                modulo(i, 5, function(err, res) {
                  isTrue(res === 0, function(err, res) {
                    if (res) {
                      console.log('Buzz');
                    } else {
                      console.log(i);
                    }
                  });
                });
              }
            });
          });
        }
      });
    });
  }
}

fizzbuzz();

[scf4]

Thank you for this fantastic contribution! Could you possibly add the FizzBuzz implementation to the /examples dir? The more examples we have, the better.

The sixers currently have a monopoly on the JavaScript ecosystem (including examples and tutorials) and examples like this are one of the only things we really have to show newcomers that there's more to JavaScript than async/await and promises and whatever the new "hot" framework and new replacement for WebPack is... but I digress. Thanks again!

[rbong]

Great idea, I've added it

[scf4]

Perfect, thanks!