Get an IAM user using an Amazon SDK

    /// <summary>
    /// Get information about an IAM user.
    /// </summary>
    /// <param name="userName">The username of the user.</param>
    /// <returns>An IAM user object.</returns>
    public async Task<User> GetUserAsync(string userName)
    {
        var response = await _IAMService.GetUserAsync(new GetUserRequest { UserName = userName });
        return response.User;
    }

###############################################################################
# function errecho
#
# This function outputs everything sent to it to STDERR (standard error output).
###############################################################################
function errecho() {
  printf "%s\n" "$*" 1>&2
}

###############################################################################
# function iam_user_exists
#
# This function checks to see if the specified AWS Identity and Access Management (IAM) user already exists.
#
# Parameters:
#       $1 - The name of the IAM user to check.
#
# Returns:
#       0 - If the user already exists.
#       1 - If the user doesn't exist.
###############################################################################
function iam_user_exists() {
  local user_name
  user_name=$1

  # Check whether the IAM user already exists.
  # We suppress all output - we're interested only in the return code.

  local errors
  errors=$(aws iam get-user \
    --user-name "$user_name" 2>&1 >/dev/null)

  local error_code=${?}

  if [[ $error_code -eq 0 ]]; then
    return 0 # 0 in Bash script means true.
  else
    if [[ $errors != *"error"*"(NoSuchEntity)"* ]]; then
      aws_cli_error_log $error_code
      errecho "Error calling iam get-user $errors"
    fi

    return 1 # 1 in Bash script means false.
  fi
}

// UserWrapper encapsulates user actions used in the examples.
// It contains an IAM service client that is used to perform user actions.
type UserWrapper struct {
	IamClient *iam.Client
}



// GetUser gets data about a user.
func (wrapper UserWrapper) GetUser(userName string) (*types.User, error) {
	var user *types.User
	result, err := wrapper.IamClient.GetUser(context.TODO(), &iam.GetUserInput{
		UserName: aws.String(userName),
	})
	if err != nil {
		var apiError smithy.APIError
		if errors.As(err, &apiError) {
			switch apiError.(type) {
			case *types.NoSuchEntityException:
				log.Printf("User %v does not exist.\n", userName)
				err = nil
			default:
				log.Printf("Couldn't get user %v. Here's why: %v\n", userName, err)
			}
		}
	} else {
		user = result.User
	}
	return user, err
}