function baseFunctions(object, props) {
      var index = -1,
          length = props.length,
          resIndex = -1,
          result = [];

      while (++index < length) {
        var key = props[index];
        if (isFunction(object[key])) {
          result[++resIndex] = key;
        }
      }
      return result;
    }
The base implementation of `_.functions` which creates an array of
`object` function property names filtered from those provided.

@private
@param {Object} object The object to inspect.
@param {Array} props The property names to filter.
@returns {Array} Returns the new array of filtered property names.