OpenGL extension ARB.fragment_layer_viewport
This module customises the behaviour of the OpenGL.raw.GL.ARB.fragment_layer_viewport to provide a more Python-friendly API
Overview (from the spec)
The geometry shader has the special built-in variables gl_Layer and gl_ViewportIndex that specify which layer and viewport primitives are rendered to. Currently the fragment shader does not know which layer or viewport the fragments are being written to without the application implementing their own interface variables between the geometry and fragment shaders.
This extension specifies that the gl_Layer and gl_ViewportIndex built-in variables are also available to the fragment shader so the application doesn't need to implement these manually.
The official definition of this extension is available here:
Return boolean indicating whether this extension is available