val empty : t
val is_empty : t ‑> bool
remove_mult set x n
removes at most n
occurrences of x
from set
.
n < 0
.update set x f
calls f n
where n
is the current multiplicity
of x
in set
(0
to indicate its absence); the result of f n
is the new multiplicity of x
.
f n < 0
.