val empty : tval to_string : t -> stringval add_range : t -> int -> int -> tadd_range t i jadds all the numbers betweeniandj(inclusive) to the set. Note that it doesn't matter which orderiandjare specified in; either way the effect is the same.
val mem : t -> int -> boolmem t itests whetheriis a member of the set.
val ranges : t -> (int * int) listranges treturns a list of all ranges that make up the set.