whole_func_string: function(len) {
  	    var s = (len || 1) / this.magnitude();
  	    this.x = s * this.x;
  	    this.y = s * this.y;
  	    return this;
          }
func_code_string: function(len) {
  	    var s = (len || 1) / this.magnitude();
  	    this.x = s * this.x;
  	    this.y = s * this.y;
  	    return this;
          }
func_documentation_string: Scale the line segment between (0,0) and me to have a length of len.