{motive : Std.Http.Chunk.ExtensionValue → Sort u} →
  (t : Std.Http.Chunk.ExtensionValue) →
    ((value : String) →
        (isValidExtensionValue : Std.Http.Chunk.IsValidExtensionValue value) →
          motive { value := value, isValidExtensionValue := isValidExtensionValue }) →
      motive t