if statement pattern [duplicate]

I don't understand this while loop structure. How does the ductCable get assigned? I see the logic test saying: "if type is IMMDuctCabe do stuff". But it looks like it is assigning that value at the same time.

items.Reset();
var item = items.Next();
while (item != null)
{
    if (item is IMMDuctCable ductCable)
    {
        var newDuctCable = new MMDuctCableClass();
        newDuctCable.cableID = ductCable.cableID; 
        ....