From language/operators

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multi sub infix:<leg>(Any,   Any)
multi sub infix:<leg>(Str:D, Str:D)

String three-way comparator. Short for less, equal or greater?.

Coerces both arguments to Str and then does a lexicographic comparison.

say 'a' leg 'b';       # OUTPUT: «Less␤» 
say 'a' leg 'a';       # OUTPUT: «Same␤» 
say 'b' leg 'a';       # OUTPUT: «More␤»