def restrict_flags(declarer, *flags)
      copy = restrict(declarer)
      copy.qualify(*flags)
      copy
    end
def restrict_flags(declarer, *flags)
      copy = restrict(declarer)
      copy.qualify(*flags)
      copy
    end
Creates a new declarer attribute which qualifies this attribute for the given declarer.

 @param declarer (see #restrict)
 @param [<Symbol>] flags the additional flags for the restricted attribute
 @return (see #restrict)