def JoinPath(stem="", *parts):
  """A sane version of os.path.join.

  The intention here is to append the stem to the path. The standard module
  removes the path if the stem begins with a /.

  Args:
     stem: The stem to join to.
     *parts: parts of the path to join. The first arg is always the root and
       directory traversal is not allowed.

  Returns:
     a normalized path.
  """
  # Ensure all path components are unicode
  parts = [SmartUnicode(path) for path in parts]

  result = (stem + NormalizePath(u"/".join(parts))).replace("//", "/")
  result = result.rstrip("/")

  return result or "/"