duration.py

class Duration(timedelta):
    def __new__(cls, value):
        if isinstance(value, timedelta):
            return cls(value.total_seconds())
        return super(Duration, cls).__new__(cls, seconds=value)

    @classmethod
    def parse(cls, s):
        sign = 1
        if s[0] == '-':
            sign = -1
            s = s[1:]
        hours, minutes = map(int, s.split('.'))
        seconds = sign * (abs(hours) * 3600 + abs(minutes) * 60)
        return cls(seconds)

    def __repr__(self):
        return '{:s}({:f})'.format(self.__class__.__name__, self.total_seconds())

    def __str__(self):
        return format(self)

    def __format__(self, frmt=None):
        if not frmt:
            frmt = '%z%Hh%M'

        value = self.total_seconds()
        sign = '-' if value < 0 else '+'
        seconds = int(abs(value))
        hours, seconds = divmod(seconds, 3600)
        minutes, seconds = divmod(seconds, 60)

        table = {'z': ('sign', '1s'),
                 'H': ('hours', '02d'),
                 'M': ('minutes', '02d'),
                 'S': ('seconds', '02d'),
                 'T': ('value', 'f')}

        def replace(m):
            value, default = table[m.group(2)]
            spec = m.group(1) or default
            return f'{{{value:}:{spec:}}}'

        return re.sub('%(\d*)(\w)', replace, frmt).format(**locals())

    def __bool__(self):
        return self.total_seconds() != 0

    def __eq__(self, other):
        return self.total_seconds() == other

    def __lt__(self, other):
        return self.total_seconds() < other

    def __sub__(self, other):
        return Duration(self.total_seconds() - other.total_seconds())