code: function(file, expression, callback) {
      if(file.length != expression.length && expression.length != callback.length)
          throw new Error("All arguments must be of the same length");
      for(var i = 0; i < file.length; i++)
          watch(file[i], expression[i], callback[i]);
  }
docs: **watchFiles**  Function to start watching an array of files  _Parameters:_  * `file`: The list of files to watch * `expression`: A list of valid expressions * `callback`: A list of `callback` objects as decribed above  _Throws:_  * `Error`: If the length of all the three supplied lists are not same