src/Utils/MixedStore.php
public function offsetGet($offset)
    {
        if ($offset === true) {
            return $this->trueValue;
        }
        if ($offset === false) {
            return $this->falseValue;
        }
        if (is_int($offset) || is_string($offset)) {
            return $this->standardStore[$offset];
        }
        if (is_float($offset)) {
            return $this->floatStore[(string) $offset];
        }
        if (is_object($offset)) {
            return $this->objectStore->offsetGet($offset);
        }
        if (is_array($offset)) {
            // offsetGet is often called directly after offsetExists, so optimize to avoid second loop:
            if ($this->lastArrayKey === $offset) {
                return $this->lastArrayValue;
            }
            foreach ($this->arrayKeys as $index => $entry) {
                if ($entry === $offset) {
                    return $this->arrayValues[$index];
                }
            }
        }
        if ($offset === null) {
            return $this->nullValue;
        }

        return null;
    }
public function offsetGet($offset)
    {
        if ($offset === true) {
            return $this->trueValue;
        }
        if ($offset === false) {
            return $this->falseValue;
        }
        if (is_int($offset) || is_string($offset)) {
            return $this->standardStore[$offset];
        }
        if (is_float($offset)) {
            return $this->floatStore[(string) $offset];
        }
        if (is_object($offset)) {
            return $this->objectStore->offsetGet($offset);
        }
        if (is_array($offset)) {
            // offsetGet is often called directly after offsetExists, so optimize to avoid second loop:
            if ($this->lastArrayKey === $offset) {
                return $this->lastArrayValue;
            }
            foreach ($this->arrayKeys as $index => $entry) {
                if ($entry === $offset) {
                    return $this->arrayValues[$index];
                }
            }
        }
        if ($offset === null) {
            return $this->nullValue;
        }

        return null;
    }
Offset to retrieve

@link http://php.net/manual/en/arrayaccess.offsetget.php

@param mixed $offset <p>
The offset to retrieve.
</p>

@return mixed Can return all value types.