GraphicsCommandCircle circle(num x, num y, num radius, [ bool antiClockwise = false ])

Draw a circle at x and y

Source 

GraphicsCommandCircle circle(num x, num y, num radius, [bool antiClockwise = false]) {
  var command = new GraphicsCommandCircle(x, y, radius, antiClockwise);
  this.addCommand(command);
  return command;
}