High-level function to call a `backend' on a `node' to generate
        code for module `module_name'.

def dump(self, backend, node):
        '''High-level function to call a `backend' on a `node' to generate
        code for module `module_name'.'''
        assert issubclass(backend, Backend)
        b = backend()
        b.attach(self)
        return b.run(node)