I'm curious how one would proceed in integrating a function of the form -
$$ \iint dx \hspace{1mm} dx' \hspace{1mm} \delta(x - x') \delta(x' - x) f(x, x') $$
My intuition (and the solution to the problem, which is given) tells me that the answer is -
$$ f(x', x) $$
but I'm having trouble convincing myself. Thanks