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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def __getVariables(self):
 """Parses the P4 env vars using 'set p4'"""

        try:
            startupinfo = None
            if os.name == 'nt':
                startupinfo = subprocess.STARTUPINFO()
                startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
            output = subprocess.check_output(['p4', 'set'], startupinfo=startupinfo)
            if six.PY3:
                output = str(output, 'utf8')
        except subprocess.CalledProcessError as err:
            LOGGER.error(err)
            return

        p4vars = {}
        for line in output.splitlines():
            if not line:
                continue
            try:
                k, v = line.split('=', 1)
            except ValueError:
                continue
            p4vars[k.strip()] = v.strip().split(' (')[0]
            if p4vars[k.strip()].startswith('(config'):
                del p4vars[k.strip()]

        self._port = self._port or os.getenv('P4PORT', p4vars.get('P4PORT'))
        self._user = self._user or os.getenv('P4USER', p4vars.get('P4USER'))
        self._client = self._client or os.getenv('P4CLIENT', p4vars.get('P4CLIENT'))