> ## Documentation Index
> Fetch the complete documentation index at: https://companyname-a7d5b98e-closes-94-guidebook-more.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Simple examples

## Maybe

```tlb theme={null}
nothing$0 {X:Type} = Maybe X;
just$1 {X:Type} value:X = Maybe X;
```

The `Maybe` combinator is used to represent optional values. In this case, the first bit indicates a value.
If the bit is `0`, the value is not serialized and skipped. If the bit is `1`, the value follows and is serialized.

## Either

```tlb theme={null}
left$0 {X:Type} {Y:Type} value:X = Either X Y;
right$1 {X:Type} {Y:Type} value:Y = Either X Y;
```

The `Either` type is used when one of two possible result types may be present.
The choice of type depends on the prefix bit. If the prefix bit is `0`, then the left type is serialized. If it is `1`, the right type is serialized.

This construct is used, for example, when serializing messages, where the body is either included directly
in the main cell or stored in a separate referenced cell.

## Both

```tlb theme={null}
pair$_ {X:Type} {Y:Type} first:X second:Y = Both X Y;
```

The `Both` type variation is used exclusively with regular pairs, where both types are serialized sequentially without any conditions.

## VarUInteger n

```tlb theme={null}
var_uint$_ {n:#} len:(#< n) value:(uint (len * 8)) = VarUInteger n;
```

The combinator is parameterized by a natural number `n`, represented in curly brackets. For a given `n`, `VarUInteger n`
describes the serialization of a natural number `m`, which in its binary representation contains no more than `n * 8` bits.

First, the number of bytes required for writing `m`, that is called `len`, is serialized into $\lceil \log_{2}n \rceil$ bits as an unsigned
big-endian integer. Then `m` itself is serialized as a `uint` on `len*8` bits. Thus, the size of the serialization of a particular `m` through the
combinator `VarUInteger n` depends on `m`.

This type is used as the representation of an amount of toncoins stored on the account.