username = il_mio('username')
 password = la_mia('password')

base64string = base64.encodestring('%s:%s' % (username, password)).replace('\n', '')
authenticationHeader = {
  "SOAPAction": "",
  "Authorization": "Basic %s" % base64string
}

cliente=Client(wsdl_url, headers=authenticationHeader)

var = dict(utenteApplicativo=username,
               carrello=dict(
                   idCarrello=id_carrello,
                   itemCarrello=dict(
                       causale=causale,
                       codiceEnte=cod_ente,
                       importo=importo,
                       importoUnitario=imp_u,
                       quantitaItem=quantita,
                   )
               )
            )