New Constructs:
Tally
with
Key
IV
Index
<<
>>
{⍺(≢⍵)}⌸y
1.5
{⊖sort⍕
{⍺(≢⍵)}⌸
⍵[;⍳3]} {⊖⍕(↓b⌿t),⍪-2-/¯1,b/⍳⍴b←∨/(1↓t⍪' ')≠t←sort ⍵[;⍳3]}