src/Zicht/Itertools/lib/Containers/KeyValuePair.php
public function offsetSet($offset, $value)
    {
        if ($offset === 0 || $offset === 'key') {
            $this->key = $value;
            return;
        }

        if ($offset === 1 || $offset === 'value') {
            $this->value = $value;
            return;
        }

        throw new \InvalidArgumentException('$OFFSET must be either 0, 1, "key", or "value"');
    }
public function offsetSet($offset, $value)
    {
        if ($offset === 0 || $offset === 'key') {
            $this->key = $value;
            return;
        }

        if ($offset === 1 || $offset === 'value') {
            $this->value = $value;
            return;
        }

        throw new \InvalidArgumentException('$OFFSET must be either 0, 1, "key", or "value"');
    }
{@inheritdoc}