def alias(aliasPath, sourcePath):
    """
    I am not a very good aliaser. But I'm the best I can be. If I'm
    aliasing to a Resource that generates links, and it uses any parts
    of request.prepath to do so, the links will not be relative to the
    aliased path, but rather to the aliased-to path. That I can't
    alias static.File directory listings that nicely. However, I can
    still be useful, as many resources will play nice.
    """
    sourcePath = sourcePath.split('/')
    aliasPath = aliasPath.split('/')
    def rewriter(request):
        if request.postpath[:len(aliasPath)] == aliasPath:
            after = request.postpath[len(aliasPath):]
            request.postpath = sourcePath + after
            request.path = '/'+'/'.join(request.prepath+request.postpath)
    return rewriter

    I am not a very good aliaser. But I'm the best I can be. If I'm
    aliasing to a Resource that generates links, and it uses any parts
    of request.prepath to do so, the links will not be relative to the
    aliased path, but rather to the aliased-to path. That I can't
    alias static.File directory listings that nicely. However, I can
    still be useful, as many resources will play nice.
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/rewrite.py