(examples-for ⋂

("returns a single arg"
 (⋂ '(a b c))
 (a b c))

("returns a single nil arg"
 (⋂ nil)
 nil)

("returns intersection of two args"
 (⋂ '(a b c) '(a b d))
 (a b))

("returns intersection of list and nil"
 (⋂ '(a b c) nil)
 nil)

("returns intersection of nil and list"
 (⋂ nil '(a b c))
 nil)

("returns intersection of three args"
 (⋂ '(a b c d e) '(a b c d f) '(z b c d g))
 (b c d))

("returns intersection of list, nil, and another list"
 (⋂ '(a b c d e) nil '(z b c d g))
 nil)

("returns intersection of four args"
 (⋂ '(a b c d e) '(a b c d f) '(z b d c g) '(z y g c d))
 (c d)))