class Duration:

""" Relative duration of time.

"""

def __init__(self, attos):

# TODO: use attos here, or maybe normal seconds?

self.attos = attos

def __repr__(self):

return f"Duration[{self.attos}]"

@classmethod

def from_days(cls, days):

return cls.from_hours(days * 24)

@classmethod

def from_hours(cls, hours):

return cls.from_minutes(hours * 60)

@classmethod

def from_minutes(cls, minutes):

return cls.from_seconds(minutes * 60)

@classmethod

def from_seconds(cls, seconds):

""" Create a duration with the given amount of seconds. """

return cls(seconds)

@classmethod

def from_milli_seconds(cls, millis):

""" Create a duration with the given amount of milli-seconds. """

return cls.from_seconds(millis * 1.0e-3)

@classmethod

def from_nano_seconds(cls, nanos):

""" Create a duration with the given amount of nano-seconds. """

return cls.from_seconds(nanos * 1.0e-9)

def to_seconds(self) -> float:

""" Return the amount of seconds in this duration.

"""

return self.attos

def __add__(self, other):

assert isinstance(other, Duration)

return Duration(self.attos + other.attos)

def __mul__(self, other):

if isinstance(other, (int, float)):

return Duration(self.attos * other)

else:

return NotImplemented

def __truediv__(self, other):

assert isinstance(other, (int, float))

return Duration(self.attos / other)

def __lt__(self, other):

assert isinstance(other, Duration)

return self.attos < other.attos