var EraserTool = MapTool.extend(function(base){
	var exports = {}
	exports.down = function(e, cursor){
    last_point.a = cursor.x.a
    last_point.b = cursor.y.a
    var segment = shapes.findClosestSegment(last_point)
    if (segment) {
      shapes.removeSegment(segment)
    }
  }
  exports.move = function(e, cursor){
    last_point.a = cursor.x.a
    last_point.b = cursor.y.a
    var segment = shapes.findClosestSegment(last_point)
    if (segment) {
      document.body.style.cursor = "pointer"
      last_point.a = segment.x
      last_point.b = segment.y
      cursor.x.a = cursor.x.b = last_point.a
      cursor.y.a = cursor.y.b = last_point.b
    }
    else {
      document.body.style.cursor = "crosshair"
    }
  }
  return exports
})