uniq ← {((⍳≢⍵)=⍵⍳⍵)⌿⍵}  ⍝ bad meme

   Tol←{⎕ct←⍵⍵ ⋄ ⍎(0=⎕nc'⍺')↓'⍺ ⍺⍺ ⍵'}

   (∪x) ≡ Tol 0 uniq x
1

   ⍳≢x
0 1 2 3 4 5 6 7 8 9 10
   x⍳x
0 0 1 2 3 4 5 6 7 8 9
   (⍳≢x)=x⍳x
1 0 0 0 0 0 0 0 0 0 0
   ((⍳≢x)=x⍳x)⌿x
1
 
   y←y[?⍨≢y←,(?10⍴100)∘.×1+⎕ctׯ5+?100⍴11]
   (∪y) ≡ Tol 0 uniq y
1