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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 _lookup(self, timestamp):
 """ Return the index of the value associated with "timestamp" if any, else None. Since the timestamps are floating-point values, they are considered equal if their absolute difference is smaller than self.EPSILON """


        idx = search_greater(self._values, timestamp)
        if (idx < len(self._values)
                and math.fabs(self._values[idx][0] - timestamp) < self.EPSILON):
            return idx
        return None