'Get whether the element is I{nil} as defined by having
an attribute in the I{xsi:nil="true"}
@return: True if I{nil}, else False
@rtype: boolean'

def isnil(self):

    nilattr = self.getAttribute('nil', ns=Namespace.xsins)
    if (nilattr is None):
        return False
    else:
        return (nilattr.getValue().lower() == 'true')
