For arrays, an array containing all elements present in a and not in b is returne. The order of the remaining values from a will be kept.

For multisets, the same operation is done as for arrays, except order is of course not considered.

For mappings, a mapping is returned with every key-index pair from
a whos index is not present as an index in b.
EXAMPLES
5-10	returns -5
10-2.0	returns 8.0
({1,2})-({2})	returns ({1})
([1:2,2:1])-([1:0])	returns ([2:1])