def removeReader(self, reader):
        """
        Remove a C{FileDescriptor} from notification of data available to read.
        """
        try:
            self._readers.remove(reader)
        except KeyError:
            return
        self._checkLoop()

        Remove a C{FileDescriptor} from notification of data available to read.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/posixbase.py