code: public Observable<List<VirtualMachineSizeInner>> listAsync(String location) {
          return listWithServiceResponseAsync(location).map(new Func1<ServiceResponse<List<VirtualMachineSizeInner>>, List<VirtualMachineSizeInner>>() {
              @Override
              public List<VirtualMachineSizeInner> call(ServiceResponse<List<VirtualMachineSizeInner>> response) {
                  return response.body();
              }
          });
      }
docs: Lists all available virtual machine sizes for a subscription in a location.
  
  @param location The location upon which virtual-machine-sizes is queried.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;VirtualMachineSizeInner&gt; object