lib/common.js
function(callback) {
      self._getConnection(function(err, connection) {
        if (err) {
          callback(new Error('Unable to establish connection with the master ' +
                             'process'));
          return;
        }

        self._connection = connection;
        callback();
      });
    }
function(callback) {
      self._getConnection(function(err, connection) {
        if (err) {
          callback(new Error('Unable to establish connection with the master ' +
                             'process'));
          return;
        }

        self._connection = connection;
        callback();
      });
    }
function ( callback ) { self . _getConnection ( function ( err , connection ) { if ( err ) { callback ( new Error ( 'Unable to establish connection with the master ' + 'process' ) ) ; return ; } self . _connection = connection ; callback ( ) ; } ) ; }
Obtain the connection
Obtain the connection