fnrepl←{ ⍝ Function string replacement.
⍺←⎕THIS ⍝ default current space.
1:shy←{⍵~⊂''}⍺.{ ⍝ shy rslt: changed function list.
(↓⎕NL 3 4){ ⍝ target space, names of fns (and ops).
(⎕NR ⍺){ ⍝ function source lines.
⍺≡⍵:'' ⍝ no change: ignore.
⊢⎕FX ⍵ ⍝ name of changed fn.