def validatedAttr(attr):
    """
    validatedAttr(attr)

    Static method. Determines whether the parameter begins with one
    underscore '_' but not two. Raises NotSpecialAttributeName otherwise.
    Attributes beginning with one underscore will be looked up in the
    mapped dictionary.
    """

    if len(attr) > 2 \
      and attr.startswith("_") \
      and not attr.startswith("__"):

        return attr[1:]

    raise NotSpecialAttributeName(attr)

    validatedAttr(attr)

    Static method. Determines whether the parameter begins with one
    underscore '_' but not two. Raises NotSpecialAttributeName otherwise.
    Attributes beginning with one underscore will be looked up in the
    mapped dictionary.
    
recipes/Python/496716_A_dict_proxy_metaclass/recipe-496716.py