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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 resolve_mode(self, name):
 """ From given mode name, return mode file path from ``settings.CODEMIRROR_MODES`` map. Arguments: name (string):
 Mode name. Raises: KeyError: When given name does not exist in ``settings.CODEMIRROR_MODES``. Returns: string: Mode file path. """

        if name not in settings.CODEMIRROR_MODES:
            msg = ("Given config name '{}' does not exists in "
                   "'settings.CODEMIRROR_MODES'.")
            raise UnknowModeError(msg.format(name))

        return settings.CODEMIRROR_MODES.get(name)