metrology/instruments/derive.py
def mark(self, value=1):
        """Record an event with the derive.

        :param value: counter value to record
        """
        last = self.last.get_and_set(value)
        if last <= value:
            value = value - last
        super(Derive, self).mark(value)
def mark(self, value=1):
        """Record an event with the derive.

        :param value: counter value to record
        """
        last = self.last.get_and_set(value)
        if last <= value:
            value = value - last
        super(Derive, self).mark(value)
Record an event with the derive.

        :param value: counter value to record