def delete_all(obj):
    '''Calls `delete()` on all members of `obj` that are recognized as
    instances of `pg` objects.'''
    types = tuple([
        Shader,
        Mesh,
        VertexBuffer,
        IndexBuffer,
        Texture,
        Program,
        Context,
    ])
    for name in dir(obj):
        child = getattr(obj, name)
        if isinstance(child, types):
            child.delete()
Calls `delete()` on all members of `obj` that are recognized as
    instances of `pg` objects.