"end": 659965
          }
        }
      }
    ],
    "span": {
      "start": 659950,
      "end": 659966
    }
  }
}
```

### `Block`

A reference to a parsed block of Nushell code, without any captured variables.

| Field    | Type                        |
| -------- | --------------------------- |
| **val**  | unsigned integer (block id) |
| **span** | [`Span`](#span)             |

Example:

```json
{
  "Block": {
    "val": 44500,
    "span": {
      "start": 59400,
      "end": 59480
    }
  }
}
```

### `Closure`

A reference to a parsed block of Nushell code, with variables captured from scope.

| Field    | Type            |
| -------- | --------------- |
| **val**  | `Closure`       |
| **span** | [`Span`](#span) |

`Closure` is defined as:

| Field        | Type                                                          |
| ------------ | ------------------------------------------------------------- |
| **block_id** | unsigned integer                                              |
| **captures** | array of pairs (unsigned integer `var_id`, [`Value`](#value)) |

The plugin **should not** try to inspect the contents of the closure. It is recommended that this is only used as an argument to the [`EvalClosure` engine call](#evalclosure-engine-call). The exact representation of a closure is likely to change in the future to avoid serializing all of the captures.

Example:

```nu
let foo = "bar"
{ || $foo }
```

```json
{
  "Closure": {
    "val": {
      "block_id": 1965,
      "captures": [
        [
          862,
          {
            "String": {
              "val": "bar",
              "span": {
                "start": 660030,
                "end": 660041
              }
            }
          }
        ]
      ]
    },
    "span": {
      "start": 660030,
      "end": 660041
    }
  }
}
```

### `Nothing`

The absence of a value, represented by `null` within Nushell.

| Field    | Type            |
| -------- | --------------- |
| **span** | [`Span`](#span) |

Example:

```nu
null
```

```json
{
  "Nothing": {
    "span": {
      "start": 64550,
      "end": 64554
    }
  }
}
```

### `Error`

An error contained within a value. Trying to operate on the value will most likely cause the error to be forwarded. When writing plugins, error values should typically be handled by returning the error from the command when encountered.

| Field    | Type                            |
| -------- | ------------------------------- |
| **val**  | [`LabeledError`](#labelederror) |
| **span** | [`Span`](#span)                 |

Example:

```nu
error make {
  msg: "foo"
  label: {
    text: "bar"
    span: {
      start: 0
      end: 0
    }
  }
}
```

```json
{
  "Error": {
    "val": {
      "msg": "foo",
      "labels": [
        {
          "text": "bar",
          "span": {
            "start": 0,
            "end": 0
          }
        }
      ],
      "code": null,
      "url": null,
      "help": null,
      "inner": []
    }
  }
}
```

### `Binary`

An array of raw bytes. This is sometimes returned from operations that detect data that isn't valid as UTF-8, but can also be created with `into binary` or binary literals.

| Field    | Type            |
| -------- | --------------- |
| **val**  | byte array      |
| **span** | [`Span`](#span) |

Note that the encoding of byte arrays in [JSON](#json) and [MessagePack](#messagepack) is different - the former uses an array of numbers, but the latter uses the native byte array support.

Example:

```nu
0x[aa bb cc dd]
```

```json
{
  "Binary": {
    "val": [170, 187, 204, 221],
    "span": {
      "start": 659637,
      "end": 659652
    }
  }
}
```

### `CellPath`

Represents a path into subfields of lists, records, and tables.

| Field    | Type            |
| -------- | --------------- |
| **val**  | `CellPath`      |
| **span** | [`Span`](#span) |

`CellPath` is defined as:

| Field       | Type         |
| ----------- | ------------ |
| **members** | `PathMember` |