def _keywords_only(f):
    """
    Decorate a function so all its arguments must be passed by keyword.

    A useful utility for decorators that take arguments so that they don't
    accidentally get passed the thing they're decorating as their first
    argument.

    Only works for methods right now.
    """
    @wraps(f)
    def g(self, **kw):
        return f(self, **kw)
    return g
Decorate a function so all its arguments must be passed by keyword.

    A useful utility for decorators that take arguments so that they don't
    accidentally get passed the thing they're decorating as their first
    argument.

    Only works for methods right now.