DB<137> %lexicon=("day"=>1,"night"=>2,"knight"=>3)
 => ("day", 1, "night", 2, "knight", 3)

  DB<138> $pattern = join "|",sort {length($b)<=>length( $a) } keys %lexicon
 => "knight|night|day"

  DB<139> $tweet= "today I will knight a guy I met last night"
 => "today I will knight a guy I met last night"

  DB<140> @matches =  ( $tweet =~ /($pattern)/g )
 => ("day", "knight", "night")

  DB<141>  @lexicon{@matches}
 => (1, 3, 2)