arangosh> var explain = require("org/arangodb/aql/explainer").explain;
arangosh> db.example.ensureSkiplist("a", "b");
{ 
  "id" : "example/600634251", 
  "type" : "skiplist", 
  "fields" : [ 
    "a", 
    "b" 
  ], 
  "unique" : false, 
  "sparse" : false, 
  "isNewlyCreated" : true, 
  "code" : 201 
}
arangosh> explain("FOR doc IN example FILTER doc.a < 23 RETURN doc", {colors:false});
Query string:
 FOR doc IN example FILTER doc.a < 23 RETURN doc

Execution plan:
 Id   NodeType         Est.   Comment
  1   SingletonNode       1   * ROOT
  6   IndexRangeNode      1     - FOR doc IN example   /* skiplist index scan */
  5   ReturnNode          1       - RETURN doc

Indexes used:
 Id   Type       Collection   Unique   Sparse   Selectivity Est.   Fields     Ranges
  6   skiplist   example      false    false                 n/a   `a`, `b`   [ `a` < 23 ]

Optimization rules applied:
 Id   RuleName
  1   use-index-range
  2   remove-filter-covered-by-index