code: public void removeTangoPipeListener(ITangoPipeListener listener, String attrName)
              throws DevFailed {
          synchronized (moni) {
              TangoPipe tangoPipe;
              String key = deviceName+"/"+attrName;
              if ((tangoPipe = tango_pipe_source.get(key)) != null)
                  tangoPipe.removeTangoPipeListener(listener);
          }
      }
docs: =======================================================================