anchor: love.graphics.discard
  Discards (trashes) the contents of the screen or active Canvas. This is a performance optimization function with niche use cases.
  
  If the active Canvas has just been changed and the 'replace' BlendMode is about to be used to draw something which covers the entire screen, calling love.graphics.discard rather than calling love.graphics.clear or doing nothing may improve performance on mobile devices.
  
  On some desktop systems this function may do nothing.
  love.graphics.discard( discardcolor, discardstencil )
  discardcolor (true) boolean Whether to discard the texture(s) of the active Canvas(es) (the contents of the screen if no Canvas is active.)
  discardstencil (true) boolean Whether to discard the contents of the stencil buffer of the screen / active Canvas.
  love.graphics.discard( discardcolors, discardstencil )
  discardcolors table An array containing boolean values indicating whether to discard the texture of each active Canvas, when multiple simultaneous Canvases are active.
  discardstencil (true) boolean Whether to discard the contents of the stencil buffer of the screen / active Canvas.