code: @Override
      public EnableUserResult enableUser(EnableUserRequest request) {
          request = beforeClientExecution(request);
          return executeEnableUser(request);
      }
docs: <p>
  Enables a user in the user pool. After being enabled, users can sign in to AppStream 2.0 and open applications
  from the stacks to which they are assigned.
  </p>
  
  @param enableUserRequest
  @return Result of the EnableUser operation returned by the service.
  @throws ResourceNotFoundException
  The specified resource was not found.
  @throws InvalidAccountStatusException
  The resource cannot be created because your AWS account is suspended. For assistance, contact AWS
  Support.
  @sample AmazonAppStream.EnableUser
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/appstream-2016-12-01/EnableUser" target="_top">AWS API
  Documentation</a>