Ds\Map::union

Creates a new map using values from the current instance and another map

&reftitle.description; public `Ds\Map` `Ds\Map::union` `Ds\Map` `map`

Creates a new map that contains the pairs of the current instance as well as the pairs of another `map`.

`A ∪ B = {x: x ∈ A ∨ x ∈ B}`

Values of the current instance will be overwritten by those provided where keys are equal.

&reftitle.parameters;

`map`

- The other map, to combine with the current instance.

&reftitle.returnvalues;

A new map containing all the pairs of the current instance as well as another `map`.

&reftitle.seealso;

- Union on Wikipedia

&reftitle.examples;

### `Ds\Map::union` example

    <?php
    $a = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
    $b = new \Ds\Map(["b" => 3, "c" => 4, "d" => 5]);

    print_r($a->union($b));
    ?>

&example.outputs.similar;

    Ds\Map Object
    (
        [0] => Ds\Pair Object
            (
                [key] => a
                [value] => 1
            )

        [1] => Ds\Pair Object
            (
                [key] => b
                [value] => 3
            )

        [2] => Ds\Pair Object
            (
                [key] => c
                [value] => 4
            )

        [3] => Ds\Pair Object
            (
                [key] => d
                [value] => 5
            )

    )