# `first` is made an alias of `peek` to avoid bad surprises
redef fun first do return peek
- # Take and return all elements until the queue is empty
- # ensure `is_empty`
- # ensure `result.length == old(length)`
- # ensure `not old(is_empty) implies result.first == old(peek)`
+ # Take and return all elements until the queue is empty.
+ #
+ # Ensure:
+ # * `is_empty`
+ # * `result.length == old(length)`
+ # * `not old(is_empty) implies result.first == old(peek)`
+ #
# ~~~
# var a = (new Array[Int]).as_lifo
# a.add 1