'Visit a list of nodes as block in a frame.  If the current frame
is no buffer a dummy ``if 0: yield None`` is written automatically
unless the force_generator parameter is set to False.'

def blockvisit(self, nodes, frame):

    if (frame.buffer is None):
        self.writeline('if    0:    yield    None')
    else:
        self.writeline('pass')
    try:
        for node in nodes:
            self.visit(node, frame)
    except CompilerExit:
        pass
