From type/Supply

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method share(Supply:D: --> Supply:D)

Creates a live supply from an on-demand supply, thus making it possible to share the values of the on-demand supply on multiple taps, instead of each tap seeing its own copy of all values from the on-demand supply.

# this says in turn: "first 1" "first 2" "second 2" "first 3" "second 3" 
my $s = Supply.interval(1).share;
$s.tap: { "first $_".say };
sleep 1.1;
$s.tap: { "second $_".say };
sleep 2