Function iteratee

underscore.js:777–779

(value, context)

  // `_.iteratee` if they want additional predicate/iteratee shorthand styles.
  // This abstraction hides the internal-only `argCount` argument.
  function iteratee(value, context) {
    return baseIteratee(value, context, Infinity);
  }
  _$1.iteratee = iteratee;

  // The function we call internally to generate a callback. It invokes