koa-logger.js
function format (str, tokens) {
  for (let i = 0; i < tokens.length; i++) {
    str = str.replace(tokens[i].token, tokens[i].replacement)
  }
  return str
}
function format (str, tokens) {
  for (let i = 0; i < tokens.length; i++) {
    str = str.replace(tokens[i].token, tokens[i].replacement)
  }
  return str
}
function format ( str , tokens ) { for ( let i = 0 ; i < tokens . length ; i ++ ) { str = str . replace ( tokens [ i ] . token , tokens [ i ] . replacement ) } return str }
Return formatted log line.

@param  {String} str
@param  {IncomingMessage} req
@param  {ServerResponse} res
@return {String}
@api private
Return formatted log line .