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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 track_trace(self, name, properties=None, severity=None):
 """Sends a single trace statement. Args: name (str). the trace statement.\n properties (dict). the set of custom properties the client wants attached to this data item. (defaults to: None)\n severity (str). the severity level of this trace, one of DEBUG, INFO, WARNING, ERROR, CRITICAL """

        data = channel.contracts.MessageData()
        data.message = name or NULL_CONSTANT_STRING
        if properties:
            data.properties = properties
        if severity is not None:
            data.severity_level = channel.contracts.MessageData.PYTHON_LOGGING_LEVELS.get(severity)

        self.track(data, self._context)