Escape a string in an OAuth-compatible fashion.

    TODO: verify whether this can in fact be used for OAuth 2

def escape(u):
    """Escape a string in an OAuth-compatible fashion.

    TODO: verify whether this can in fact be used for OAuth 2

    """
    if not isinstance(u, unicode_type):
        raise ValueError('Only unicode objects are escapable.')
    return quote(u.encode('utf-8'), safe=b'~')