FWIW, the last of the mandatory ones!

I.e. you can define following prototypes as long as they are marked optional with a semicolon.

Trouble here is the scalar context!

  DB<237> sub tst (_;@) { dd \@_ }

  DB<238> $_=666; @a='a'..'c'; $a='A'

  DB<239> tst
[666]

  DB<240> tst $a,1,2,3
["A", 1, 2, 3]

  DB<241> tst $a,@a
["A", "a", "b", "c"]

  DB<242> tst @a                         # OOPS
[3]
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