# Utils.Multimap¶

This document is auto-generated for Owl’s APIs. #12 entries have been extracted.

Github: {Signature} {Implementation}

## Basic functions¶

```
val empty : 'a t
```

The empty multimap.

```
val is_empty : 'a t -> bool
```

Check whether the multimap is empty.

```
val mem : key -> 'a t -> bool
```

`mem k m`

returns true is the multimap`m`

contains at least one binding- for
`k`

, false otherwise.

```
val add : key -> 'a -> 'a t -> 'a t
```

`add k v m`

returns a multimap containing the same bindings as`m`

, plus a- binding from
`k`

to`v`

. Previous bindings for`k`

are hidden by the new binding (they can be restored by calling`remove k m`

).

```
val remove : key -> 'a t -> 'a t
```

`remove k v m`

returns a multimap with the same bindings as`m`

, except- for the binding of
`k`

: the last value that was bound to it is removed. If there is no binding for`k`

in`m`

, raises Not_found.

```
val find : key -> 'a t -> 'a
```

`find k m`

returns the last added binding of`k`

in`m`

, or raises`Not_found`

if there is no such binding.

```
val max_binding : 'a t -> key * 'a
```

`max_binding m`

returns the greatest binding in`m`

. Raises`Not_found`

- if
`m`

is empty.

```
val find_first_opt : (key -> bool) -> 'a t -> (key * 'a) option
```

`find_first_opt f m`

returns the first binding`(k, v)`

such that`f k`

,- or
`None`

if no such binding exists. The function`f`

has to be nondecreasing. Time complexity is O(log n).