except
Exclude items from a list
x except y except[x;y]
Where
xis a listyis a list or atom
returns a list of all items of x that are not (items of) y.
q)1 2 3 except 2
1 3
q)1 2 3 4 1 3 except 2 3
1 4 1
except uses Find to identify items of x in y.