# XPath "function" elements that transform their subpaths

import xpath

##### Functions

funcs = {}

def process(path):

    if path == []: return path

    path[1:] = process(path[1:])

    name = path[0].name

    if name.startswith('_') and name in funcs: return funcs[name](path)

    else: return path

#### XPath functions

# Function names must start with _ to avoid collisions with real tags

# Functions take arguments (path)

def _for(items):

    return None

funcs['_for'] = _for