oap.js
function checkRequired(k, cb) {
    if (k in args)
      return cb(null);
    else
      return cb(buildError(k, 'argument missing'));
  }
function checkRequired(k, cb) {
    if (k in args)
      return cb(null);
    else
      return cb(buildError(k, 'argument missing'));
  }
function checkRequired ( k , cb ) { if ( k in args ) return cb ( null ) ; else return cb ( buildError ( k , 'argument missing' ) ) ; }
The argument checking functions
The argument checking functions