code: function(p) {
              p = point(p);
              // Invert the y-axis.
  	    var y = -(p.y - this.y);
  	    var x = p.x - this.x;
              // Makes sure that the comparison with zero takes rounding errors into account.
              var PRECISION = 10;
              // Note that `atan2` is not defined for `x`, `y` both equal zero.
  	    var rad = (y.toFixed(PRECISION) == 0 && x.toFixed(PRECISION) == 0) ? 0 : atan2(y, x); 
  
              // Correction for III. and IV. quadrant.
  	    if (rad < 0) { 
  	        rad = 2*PI + rad;
  	    }
  	    return 180*rad / PI;
          }
docs: Compute the angle between me and `p` and the x axis. (cartesian-to-polar coordinates conversion) Return theta angle in degrees.