anchor: love.physics.newPulleyJoint
  Creates a PulleyJoint to join two bodies to each other and the ground.
  
  The pulley joint simulates a pulley with an optional block and tackle. If the ratio parameter has a value different from one, then the simulated rope extends faster on one side than the other. In a pulley joint the total length of the simulated rope is the constant length1 + ratio * length2, which is set when the pulley joint is created.
  
  Pulley joints can behave unpredictably if one side is fully extended. It is recommended that the method setMaxLengths  be used to constrain the maximum lengths each side can attain.
  joint = love.physics.newPulleyJoint( body1, body2, gx1, gy1, gx2, gy2, x1, y1, x2, y2, ratio, collideConnected )
  body1 Body The first body to connect with a pulley joint.
  body2 Body The second body to connect with a pulley joint.
  gx1 number The x coordinate of the first body's ground anchor.
  gy1 number The y coordinate of the first body's ground anchor.
  gx2 number The x coordinate of the second body's ground anchor.
  gy2 number The y coordinate of the second body's ground anchor.
  x1 number The x coordinate of the pulley joint anchor in the first body.
  y1 number The y coordinate of the pulley joint anchor in the first body.
  x2 number The x coordinate of the pulley joint anchor in the second body.
  y2 number The y coordinate of the pulley joint anchor in the second body.
  ratio (1) number The joint ratio.
  collideConnected (true) boolean Specifies whether the two bodies should collide with each other.
  joint PulleyJoint The new pulley joint.