This file prints hello world If any error It shows the error message.
file = (string) filepath of the file to read
data = (string or buffer) the data you want to write to the file
encoding = (optional string) the encoding of the data. Possible encodings are 'ascii', 'utf8', and 'base64'. If no encoding provided, then 'utf8' is assumed.
callback = (optional function (err) {}) If there is no error, err === null, otherwise err contains the error message.