def preauthChild(self, path):
newpath = abspath(joinpath(self.path, normpath(path)))<EOL>if not newpath.startswith(self.path):<EOL><INDENT>raise InsecurePath("<STR_LIT>" % (newpath, self.path))<EOL><DEDENT>return self.clonePath(newpath)<EOL>
Use me if `path' might have slashes in it, but you know they're safe.

(NOT slashes at the beginning. It still needs to be a _child_).