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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 exec_psql(self, command, psql_opts=['-qtA']):
 """ Execute a ``psql`` command inside a running container. By default the container's database is connected to. :param command: the command to run (passed to ``-c``) :param psql_opts: a list of extra options to pass to ``psql`` :returns: a tuple of the command exit code and output """

        cmd = ['psql'] + psql_opts + [
            '--dbname', self.database,
            '-U', self.user,
            '-c', command,
        ]
        return self.inner().exec_run(cmd, user='postgres')