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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 top(self, container, ps_args=None):
 """ Display the running processes of a container. Args: container (str):
 The container to inspect ps_args (str):
 An optional arguments passed to ps (e.g. ``aux``) Returns: (str):
 The output of the top Raises: :py:class:`docker.errors.APIError` If the server returns an error. """

        u = self._url("/containers/{0}/top", container)
        params = {}
        if ps_args is not None:
            params['ps_args'] = ps_args
        return self._result(self._get(u, params=params), True)