demo code not right on MAC

[AceMood]

The demo code in README.md
`var cp = require('child_process'),
psTree = require('ps-tree');

var child = cp.exec("node -e 'while (true);'", function () { /.../ });

psTree(child.pid, function (err, children) {
cp.spawn('kill', ['-9'].concat(children.map(function (p) { return p.PID })));
});`

seems have no children in psTree callback on MAC platform. Node version is 10.16.3 LTS

[AceMood]

@indexzero

[nelsonic]

@AceMood could you please add more detail on exactly what version of Mac OS you are using? 💻
We all use Mac for our dev work and have never had an issue with running ps-tree on our machines ... 💭

Could be worth adding a Mac/OSX test on CI to get 3rd party confirmation that this is working. 💡