code: function _gpfWebTagFlattenChildren (array, callback) {
      array.forEach(function (item) {
          if (_gpfIsArray(item)) {
              _gpfWebTagFlattenChildren(item, callback);
          } else {
              callback(item);
          }
      });
  }
docs: Apply the callback to each array item,
  process recursively if the array item is an array
  
  @param {Array} array array of items
  @param {Function} callback Function to apply on each array item
  @since 0.2.1