def communicate(self):
        """Retrieve information."""
        self._communicate_first = True
        self._process.waitForFinished()

        enco = self._get_encoding()
        if self._partial_stdout is None:
            raw_stdout = self._process.readAllStandardOutput()
            stdout = handle_qbytearray(raw_stdout, enco)
        else:
            stdout = self._partial_stdout

        raw_stderr = self._process.readAllStandardError()
        stderr = handle_qbytearray(raw_stderr, enco)
        result = [stdout.encode(enco), stderr.encode(enco)]

        if PY2:
            stderr = stderr.decode()
        result[-1] = ''

        self._result = result

        if not self._fired:
            self.sig_finished.emit(self, result[0], result[-1])

        self._fired = True

        return result
Retrieve information.