'Get whether the I{ns} is to B{not} be normalized.
@param ns: A namespace.
@type ns: (p,u)
@return: True if to be skipped.
@rtype: boolean'

def skip(self, ns):

    return ((ns is None) or (ns == Namespace.default) or (ns == Namespace.xsdns) or (ns == Namespace.xsins) or (ns == Namespace.xmlns))
