'Build the B{<Envelope/>} for an soap outbound message.
@param header: The soap message B{header}.
@type header: L{Element}
@param body: The soap message B{body}.
@type body: L{Element}
@return: The soap envelope containing the body and header.
@rtype: L{Element}'

def envelope(self, header, body):

    env = Element('Envelope', ns=envns)
    env.addPrefix(Namespace.xsins[0], Namespace.xsins[1])
    env.append(header)
    env.append(body)
    return env
