# Sample Function

The following is a sample Lambda function that receives Amazon Cognito User Pools pre-token-gen event as an input and writes some of the record data to CloudWatch Logs. (Note that by default anything written to Console will be logged as CloudWatch Logs events.)

Please see instructions for setting up the Cognito triggers at https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-identity-pools-working-with-aws-lambda-triggers.html .

```go
package main

import (
    "fmt"

    "github.com/aws/aws-lambda-go/lambda"
    "github.com/aws/aws-lambda-go/events"
)

func handler(event events.CognitoEventUserPoolsPreTokenGen) (events.CognitoEventUserPoolsPreTokenGen, error) {
    fmt.Printf("PreTokenGen of user: %s\n", event.UserName)
    event.Response.ClaimOverrideDetails.ClaimsToSupress = []string{"family_name"}
    return event, nil
}

func main() {
  lambda.Start(handler)
}
```
