---
title: Input Check (NeMo Guardrail)
type: guardrail
provider: nvidia
category: safety
source: 'https://github.com/NVIDIA-NeMo/Guardrails'
license: Apache-2.0
tags:
  - guardrail
  - nemo
  - rails
  - colang
dateAdded: '2025-12-19'
featured: false
origin: official
language: en
description: >-
  flow self check input $allowed = await SelfCheckInputAction if not $allowed if
  $system.config.enable_rails_exceptions send InputRailException(message=
---

```coffee
flow self check input
  $allowed = await SelfCheckInputAction

  if not $allowed
    if $system.config.enable_rails_exceptions
      send InputRailException(message="Input not allowed. The input was blocked by the 'self check input' flow.")
    else
      bot refuse to respond
    abort
```