Intersection of two sets or of two lists : intersect

intersect is an infixed operator.
intersect takes as argument two sets or two lists.
intersect returns the intersection set of the arguments.
Input :

set[1,2,3,4] intersect set[5,6,3,4]

Or :

%{1,2,3,4%} intersect %{5,6,3,4%}

Output :

$\llbracket$3,4 $\rrbracket$

Input :

[1,2,3,4] intersect [5,6,3,4]

Output :

$\llbracket$3,4 $\rrbracket$