Use multiple namespace in wash_out gem in ruby

Question

I have following request to be created in my SOAP API and using this gem https://github.com/inossidabile/wash_out/

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Header>
    <OGHeader xmlns="http://example.com">
    </OGHeader>
  </soap:Header>
  <soap:Body>
    <BookingRequest xmlns="http://example.com/Booking.wsdl">
      <Reservation Action="CREATE">
        <UniqueIDList xmlns="http://example.com/Unique/">
          <UniqueID type="FAR" xmlns="www.uio.com/Common/">201801111429</UniqueID>
        </UniqueIDList>
      </Reservation>
    </BookingRequest >
  </soap:Body>
</soap:Envelope>

How to use wash_out to create such request with particular namespace defined in each xmlns?