function countHolders(array, placeholder) {
    var length = array.length,
        result = 0;

    while (length--) {
      if (array[length] === placeholder) {
        ++result;
      }
    }
    return result;
  }
Gets the number of `placeholder` occurrences in `array`.

@private
@param {Array} array The array to inspect.
@param {*} placeholder The placeholder to search for.
@returns {number} Returns the placeholder count.