function SqrOsc(freq) {
    oscillator_classCallCheck(this, SqrOsc);
    return _super4.call(this, freq, 'square');
  }
Constructor: <code>new p5.SqrOsc()</code>.
 This creates a Square Wave Oscillator and is
 equivalent to <code> new p5.Oscillator('square')
 </code> or creating a p5.Oscillator and then calling
 its method <code>setType('square')</code>.
 See p5.Oscillator for methods.

 @class  p5.SqrOsc
 @constructor
 @extends p5.Oscillator
 @param {Number} [freq] Set the frequency