def _guard_with_as(self, current_inst):
        """Checks if the next instruction after a SETUP_WITH is something other
        than a POP_TOP, if it is something else it'll be some sort of store
        which is not supported (this corresponds to `with CTXMGR as VAR(S)`)."""
        if current_inst.opname == "SETUP_WITH":
            next_op = self.bytecode[current_inst.next].opname
            if next_op != "POP_TOP":
                msg = ("The 'with (context manager) as "
                       "(variable):' construct is not "
                       "supported.")
                raise UnsupportedError(msg)
Checks if the next instruction after a SETUP_WITH is something other
        than a POP_TOP, if it is something else it'll be some sort of store
        which is not supported (this corresponds to `with CTXMGR as VAR(S)`).
numba/core/controlflow.py