feat: iteration protocols

src/util/collection.ts

@@ -1,8 +1,9 @@
-import { isNil, isString, isObject, isArray } from './underscore'
+import { isNil, isString, isObject, isArray, isIterable } from './underscore'
 
 export function toEnumerable (val: any) {
   if (isArray(val)) return val
   if (isString(val) && val.length > 0) return [val]
+  if (isIterable(val)) return Array.from(val)
   if (isObject(val)) return Object.keys(val).map((key) => [key, val[key]])
   return []
 }

src/util/underscore.ts

@@ -60,6 +60,10 @@ export function isArray (value: any): value is any[] {
   return toString.call(value) === '[object Array]'
 }
 
+export function isIterable (value: any): value is Iterable<any> {
+  return isObject(value) && Symbol.iterator in value
+}
+
 /*
  * Iterates over own enumerable string keyed properties of an object and invokes iteratee for each property.
  * The iteratee is invoked with three arguments: (value, key, object).