How to use the muffin.plugins.jade.ExtendCompiler function in muffin

def load_template(self, path):
        """ Load and compile a template. """
        if not path.startswith('/'):
            path = op.join(self.options['template_folder'], path)

        with open(path, 'rb') as f:
            source = f.read().decode(self.options['encoding'])

        return ExtendCompiler(
            pyjade.parser.Parser(source).parse(), pretty=self.options['pretty'],
            env=self, compileDebug=True
        )

def __init__(self, node, env, **options):
        """ Initialize the compiler. """
        super(ExtendCompiler, self).__init__(node, **options)
        self.env = env
        self.blocks = {node.name: node for node in self.node.nodes if isinstance(node, CodeBlock)}
        while self.node.nodes and isinstance(self.node.nodes[0], Extends):
            compiler = self.env.get_template(self.node.nodes[0].path)
            self.node = compiler.node
            for cblock in compiler.blocks.values():
                if cblock.name in self.blocks:
                    sblock = self.blocks[cblock.name]
                    if sblock.mode == 'prepend':
                        sblock.nodes = sblock.nodes + cblock.nodes
                    elif sblock.mode == 'append':
                        sblock.nodes = cblock.nodes + sblock.nodes
                else:
                    self.blocks[cblock.name] = cblock