public function testAllKeysExist()
{
$this->assertTrue(\Airship\all_keys_exist(['a', 'b'], ['a' => 1, 'b' => 2, 'c' => 'three']), 'All keys should be found present.');
$this->assertTrue(\Airship\all_keys_exist(['a', 'b', 'c'], ['a' => 1, 'b' => 2, 'c' => 'three']), 'All keys should be found present.');
$this->assertFalse(\Airship\all_keys_exist(['a', 'd'], ['a' => 1, 'b' => 2, 'c' => 'three']), 'The key, d, should not have been present.');
}