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// cheap lodash replacements
export function memoize(fn) {
let result = null;
const memoized = () => {
if (result == null) {
result = fn();
}
return result;
};
return memoized;
}
/**
* drop-in replacement for _.without
*/
export function without(items, item) {
return items.filter(i => i !== item);
}
export function union(itemsA, itemsB) {
const set = new Set();
const insertItem = (item) => set.add(item);
itemsA.forEach(insertItem);
itemsB.forEach(insertItem);
const result = [];
set.forEach(key => result.push(key));
return result;
}