⊃ — First / Pick⊃Y returns the first item, disclosing one enclosure. Empty arrays give their prototype.
⊃1 2 3 ⍝ 1
⊃(1 2)(3 4) ⍝ 1 2
P⊃Y follows an index path through nesting. Path items can be coordinate vectors. An empty path returns Y.
2 1⊃(1 2)(3 4) ⍝ 3
⍬⊃1 2 ⍝ 1 2
INDEX: position outside the array. Empty Each uses prototype selection instead.