code: function(polar) {
          this.theta = (this.theta + polar.theta) % (Math.PI * 2); this.rho += polar.rho;
          return this;
      }
docs: /*
  Method: $madd
  
  Adds two <Polar> instances affecting the current object. The resulting theta angle is modulo 2pi.
  
  Parameters:
  
  polar - A <Polar> instance.
  
  Returns:
  
  The changed object.