Documentation for infix (cont), infix βˆ‹ assembled from the following pages:

Language documentation: Operators Β§

From Operators

(Operators) infix (cont), infix βˆ‹ Β§

multi sub infix:<(cont)>($a,$b --> Bool:D)

Membership operator.

Returns True if $a contains $b as an element.

say (1,2,3(cont) 2# OUTPUT: Β«True␀» 
say (123βˆ‹ 4;    # OUTPUT: Β«False␀» 

Since release 2020.05, ∍ is an alias for this operator.

Language documentation: Sets, bags, and mixes Β§

From Sets, bags, and mixes

(Sets, bags, and mixes) infix (cont), infix βˆ‹ Β§

Returns True if $a contains $b as an element, else False. More information, Wikipedia definition.