code: public MockInternetGateway deleteInternetGateway(final String internetgatewayId) {
          if (internetgatewayId != null && allMockInternetGateways.containsKey(internetgatewayId)) {
              return allMockInternetGateways.remove(internetgatewayId);
          }
  
          return null;
      }
docs: Delete InternetGateway.
  
  @param internetgatewayId
  internetgatewayId to be deleted
  @return Mock InternetGateway.