What does the |= Operator mean?
<p>In some code i found this <code>|=</code> operator used to return a <code>uint</code> but i can find something about it on the internet and i wanna understand how it works and what are the return values in this case.</p>

<pre><code>public uint Mask
{
    get
    {
        uint num = 0;
        if (_0)
            num |= 1U;
        if (_1)
            num |= 2U;
        if (_2)
            num |= 4U;
        return num;
    }
}
</code></pre>

<p>a detailed answer will be much appreciated.</p>