'add the input/output header properties'

def header(self, definitions, parent, root):

    if (root is None):
        return
    header = Facade('Header')
    parent.headers.append(header)
    header.use = root.get('use', default='literal')
    ns = root.get('namespace')
    if (ns is None):
        header.namespace = definitions.tns
    else:
        prefix = root.findPrefix(ns, 'h0')
        header.namespace = (prefix, ns)
    msg = root.get('message')
    if (msg is not None):
        header.message = msg
    part = root.get('part')
    if (part is not None):
        header.part = part
