def __add__(self, other: Optional['TimerMetric']) -> 'TimerMetric':
    if (other is None):
        return self
    total: TScalar = (self._value + other._value)
    start: int = min(self._start, other._start)
    end: int = max(self._start, other._end)
    return type(self)(total, start, end)
def __add__(self, other: Optional['TimerMetric']) -> 'TimerMetric':
    if (other is None):
        return self
    total: TScalar = (self._value + other._value)
    start: int = min(self._start, other._start)
    end: int = max(self._start, other._end)
    return type(self)(total, start, end)