How to show that union and intersection of min cuts in flow chart is also a min cut

Question

The proof of this is everywhere skipped and said to be collorary of Ford-Fulkerson theorem. It's usually something like:

Let $A$ and $B$ be low cuts of a flow chart. Then $A \cup B$ and $A \cap B$ are also min cuts.

Can anyone tell me how exactly this is proved or link me a proof please?

Regards, Raxel.