Idioms:
Tye + Juerd in id=204874
sub slurp {  local( *ARGV, $/ ); @ARGV = shift; <> };

dragonchild id=376694
sub unique { my %x; grep { !$x{$_}++ } @_ }

broquaint id=374287
sub in_list {return !!grep { $_ eq $_[0] } @_[ 1 .. $#_ ];}