code: public PrefixPricingResponse getPrefixPrice(ServiceType type, String prefix) throws IOException, NexmoClientException {
          return getPrefixPrice(new PrefixPricingRequest(type, prefix));
      }
docs: Retrieve the pricing for a specified prefix.
  
  @param type   The type of service to retrieve pricing for.
  @param prefix The prefix to retrieve the pricing for.
  
  @return PrefixPricingResponse object which contains the results from the API.
  
  @throws IOException          if a network error occurred contacting the Nexmo Account API.
  @throws NexmoClientException if there was a problem with the Nexmo request or response objects.