rules:
  - id: return-nil
    patterns:
      - pattern-either:
          - pattern: |
              if $X == nil {
                      return $X
              }
          - pattern: |
              if $X != nil {
                      return ...
              }
              return $X
    message: return nil instead of nil value
    languages:
      - go
    severity: ERROR
    metadata:
      license: MIT