Huh, what's that do? It seems to assign x = x which is reminiscent of my pet "ugly" optimization: adding x = x to the top of a nested scope. It binds the x from

Huh, what's that do? It seems to assign x = x which is reminiscent of my pet "ugly" optimization: adding x = x to the top of a nested scope. It binds the x from a global scope to x in a local one. Local variable lookup can be substantialy faster given a hot enough loop.