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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 file_exists(self, fid):
 """Checks if file with provided fid exists Args: **fid**: File identifier <volume_id>,<file_name_hash> Returns: True if file exists. False if not. """

        res = self.get_file_size(fid)
        if res is not None:
            return True
        return False