code: def ftp_close(self, connId='default'):
          
          thisConn = self.__getConnection(connId)
          try:
              thisConn.quit()
              self.__removeConnection(connId)
          except Exception as e:
              try:
                  thisConn.close()
                  self.__removeConnection(connId)
              except ftplib.all_errors as x:
                  raise FtpLibraryError(str(x))
docs: Closes FTP connection. Returns None.
          Parameters:
          - connId(optional) - connection identifier. By default equals 'default'