libheap-perl 0.80-2 (amd64 binary) in ubuntu xenial

 The Heap collection of modules provide routines that manage
 a heap of elements. A heap is a partially sorted structure
 that is always able to easily extract the smallest of the
 elements in the structure (or the largest if a reversed compare
 routine is provided).
 .
 If the collection of elements is changing dynamically, the
 heap has less overhead than keeping the collection fully
 sorted.