 HELP: deque-empty?
 { $values { "deque" deque } { "?" boolean } }
 { $contract "Returns true if a deque is empty." }
-{ $notes "This operation is O(1)." } ;
+{ $notes "This operation is O(1)." }
+{ $examples
+  { $example
+    "USING: deques prettyprint unrolled-lists ;"
+    "<unrolled-list> deque-empty? ."
+    "t"
+  }
+} ;
 
 HELP: clear-deque
 { $values

HELP: slurp-deque
{ $values
     { "deque" deque } { "quot" quotation } }
{ $description "Pops off the back element of the deque and calls the quotation in a loop until the deque is empty." } ;

ARTICLE: "deques" "Deques"
"The " { $vocab-link "deques" } " vocabulary implements the deque data structure which has constant-time insertion and removal of elements at both ends."


HELP: push-front
{ $values { "obj" object } { "deque" deque } }
{ $description "Push the object onto the front of the deque." }
{ $notes "This operation is O(1)." } ;

HELP: push-front*
{ $values { "obj" object } { "deque" deque } { "node" "a node" } }
{ $contract "Push the object onto the front of the deque and return the newly created node." }
{ $notes "This operation is O(1)." }
{ $examples
  { $example
    "USING: deques dlists kernel prettyprint ;"
    "33 <hashed-dlist> push-front* node-value ."
    "33"
  }
} ;

HELP: push-back
{ $values { "obj" object } { "deque" deque } }
{ $description "Push the object onto the back of the deque." }
{ $notes "This operation is O(1)." } ;

HELP: push-back*
{ $values { "obj" object } { "deque" deque } { "node" "a node" } }
{ $contract "Push the object onto the back of the deque and return the newly created node." }
{ $notes "This operation is O(1)." } ;

HELP: push-all-back
