src/Types/Struct.php
public function offsetSet($offset, $value)
    {
        if (!is_string($offset)) {
            throw new \InvalidArgumentException('A string offset was expected');
        }
        $this->value[$offset] = $value;
    }
public function offsetSet($offset, $value)
    {
        if (!is_string($offset)) {
            throw new \InvalidArgumentException('A string offset was expected');
        }
        $this->value[$offset] = $value;
    }
Change the item at some index in the collection.

\param int $offset
Index of the item to modify.

\param mixed $value
New value for the item at the given index.

\return
This method does not return any value.