function createPartialWrapper(func, bitmask, thisArg, partials) {
  var isBind = bitmask & BIND_FLAG,
      Ctor = createCtorWrapper(func);

  function wrapper() {
    // Avoid `arguments` object use disqualifying optimizations by
    // converting it to an array before providing it `func`.
    var argsIndex = -1,
        argsLength = arguments.length,
        leftIndex = -1,
        leftLength = partials.length,
        args = Array(leftLength + argsLength);

    while (++leftIndex < leftLength) {
      args[leftIndex] = partials[leftIndex];
    }
    while (argsLength--) {
      args[leftIndex++] = arguments[++argsIndex];
    }
    var fn = (this && this !== global && this instanceof wrapper) ? Ctor : func;
    return fn.apply(isBind ? thisArg : this, args);
  }
  return wrapper;
}
Creates a function that wraps `func` and invokes it with the optional `this`
binding of `thisArg` and the `partials` prepended to those provided to
the wrapper.

@private
@param {Function} func The function to partially apply arguments to.
@param {number} bitmask The bitmask of flags. See `createWrapper` for more details.
@param {*} thisArg The `this` binding of `func`.
@param {Array} partials The arguments to prepend to those provided to the new function.
@returns {Function} Returns the new bound function.