function isSubset(s1, s2, compare) {
			var allContained = true;
			forEach(s1, function (v1) {
				var includes = false;
				forEach(s2, function (v2) {
					if (compare(v2, v1)) {
						includes = true;
					}
				});
				allContained = allContained && includes;
			});

			return allContained;
		}
Returns `true` when `s1` is a subset of `s2`, `false` otherwise

@private
@param  {Array|Set}  s1      The target value
@param  {Array|Set}  s2      The containing value
@param  {Function}  compare A comparison function, should return `true` when
                            values are considered equal
@returns {boolean} Returns `true` when `s1` is a subset of `s2`, `false`` otherwise