instance to an XML-RPC
request (or response, if the methodresponse option is used).

In addition to the data object, the following options can be given
as keyword arguments:

    methodname: the method name for a methodCall packet

    methodresponse: true to create a methodResponse packet.
    If this option is used with a tuple, the tuple must be
    a singleton (i.e. it can contain only one element).

    encoding: the packet encoding (default is UTF-8)

All byte strings in the data structure are assumed to use the
packet encoding.  Unicode strings are automatically converted,
where necessary.
rW