DB<56> $_ = "AAATTTAGTTCTTAAGGCTGACATCGGTTTACGTCAGCGTTACCCCCCAAGTTATTGGGGACTTT";

  DB<57> $threshold = 3;

  DB<58> x sort { length($b) <=> length($a) } grep { length >= $threshold } /(A+|C+|G+|T+)/g
0  'CCCCCC'
1  'GGGG'
2  'AAA'
3  'TTT'
4  'TTT'
5  'TTT'
  DB<59>