new
push_front 3.8
push_front 7.5
assign
  pop_front 7.5
  size 1
  delete
exit
front 7.5
back 3.8
count 3.8 1
count 5.9 0
count 7.5 1
head
  retrieve 7.5
  next
  retrieve 3.8
  next0
exit
pop_front 7.5
head
  retrieve 3.8
  next0
exit
front 3.8
back 3.8
pop_front 3.8
size 0
empty 1
delete
summary
exit