How to use the isodate.duration.Duration function in isodate

def test_can_convert_duration_days(self):
        duration = isodate.duration.Duration(days=1)
        delta = utils.convert_duration_to_relativedelta(duration)
        self.assertEqual(delta.days, 1)

def test_can_convert_duration_minutes(self):
        duration = isodate.duration.Duration(minutes=1)
        delta = utils.convert_duration_to_relativedelta(duration)
        self.assertEqual(delta.seconds, 60)

groups[key] = "0n"
            #print groups[key]
            groups[key] = float(groups[key][:-1].replace(',', '.'))
    if groups["years"] == 0 and groups["months"] == 0:
        ret = timedelta(days=groups["days"], hours=groups["hours"],
                        minutes=groups["minutes"], seconds=groups["seconds"],
                        weeks=groups["weeks"])
        if groups["sign"] == '-':
            ret = timedelta(0) - ret
    else:
        ret = Duration(years=groups["years"], months=groups["months"],
                       days=groups["days"], hours=groups["hours"],
                       minutes=groups["minutes"], seconds=groups["seconds"],
                       weeks=groups["weeks"])
        if groups["sign"] == '-':
            ret = Duration(0) - ret
    return ret

def to_native(self, value, context=None):
        if isinstance(value, (timedelta, Duration)):
            return value
        try:
            return parse_duration(value)
        except (ISO8601Error, TypeError):
            raise ConversionError(self.messages['parse'].format(value))
        except OverflowError as e:
            raise ConversionError(e.message)

groups[key] = "0n"
            # print groups[key]
            if key in ('years', 'months'):
                groups[key] = Decimal(groups[key][:-1].replace(',', '.'))
            else:
                # these values are passed into a timedelta object,
                # which works with floats.
                groups[key] = float(groups[key][:-1].replace(',', '.'))
    if groups["years"] == 0 and groups["months"] == 0:
        ret = timedelta(days=groups["days"], hours=groups["hours"],
                        minutes=groups["minutes"], seconds=groups["seconds"],
                        weeks=groups["weeks"])
        if groups["sign"] == '-':
            ret = timedelta(0) - ret
    else:
        ret = Duration(years=groups["years"], months=groups["months"],
                       days=groups["days"], hours=groups["hours"],
                       minutes=groups["minutes"], seconds=groups["seconds"],
                       weeks=groups["weeks"])
        if groups["sign"] == '-':
            ret = Duration(0) - ret
    return ret

it does not check, whether only the last component has fractions.
        it allows weeks specified with all other combinations

      The alternative format does not support durations with years, months or
      days set to 0.
    """
    if not isinstance(datestring, str):
        raise TypeError("Expecting a string %r" % datestring)
    match = ISO8601_PERIOD_REGEX.match(datestring)
    if not match:
        # try alternative format:
        if datestring.startswith("P"):
            durdt = parse_datetime(datestring[1:])
            if durdt.year != 0 or durdt.month != 0:
                # create Duration
                ret = Duration(days=durdt.day, seconds=durdt.second,
                               microseconds=durdt.microsecond,
                               minutes=durdt.minute, hours=durdt.hour,
                               months=durdt.month, years=durdt.year)
            else:  # FIXME: currently not possible in alternative format
                # create timedelta
                ret = timedelta(days=durdt.day, seconds=durdt.second,
                                microseconds=durdt.microsecond,
                                minutes=durdt.minute, hours=durdt.hour)
            return ret
        raise ISO8601Error("Unable to parse duration string %r" % datestring)
    groups = match.groupdict()
    for key, val in list(groups.items()):
        if key not in ('separator', 'sign'):
            if val is None:
                groups[key] = "0n"
            # print groups[key]

it does not check, whether only the last component has fractions.
        it allows weeks specified with all other combinations
      
      The alternative format does not support durations with years, months or days
      set to 0. 
    """
    if not isinstance(datestring, basestring):
        raise TypeError("Expecting a string %r" % datestring)
    match = ISO8601_PERIOD_REGEX.match(datestring)
    if not match:
        # try alternative format:
        if datestring.startswith("P"):
            durdt = parse_datetime(datestring[1:])
            if durdt.year != 0 or durdt.month != 0:
                # create Duration
                ret = Duration(days=durdt.day, seconds=durdt.second, 
                               microseconds=durdt.microsecond, 
                               minutes=durdt.minute, hours=durdt.hour, 
                               months=durdt.month, years=durdt.year)
            else: # FIXME: currently not possible in alternative format
                # create timedelta
                ret = timedelta(days=durdt.day, seconds=durdt.second, 
                                microseconds=durdt.microsecond,
                                minutes=durdt.minute, hours=durdt.hour)
            return ret
        raise ISO8601Error("Unable to parse duration string %r" % datestring)
    groups = match.groupdict()
    for key, val in groups.items():
        if key not in ('separator', 'sign'):
            if val is None:
                groups[key] = "0n"
            #print groups[key]

it does not check, whether only the last component has fractions.
        it allows weeks specified with all other combinations

      The alternative format does not support durations with years, months or
      days set to 0.
    """
    if not isinstance(datestring, basestring):
        raise TypeError("Expecting a string %r" % datestring)
    match = ISO8601_PERIOD_REGEX.match(datestring)
    if not match:
        # try alternative format:
        if datestring.startswith("P"):
            durdt = parse_datetime(datestring[1:])
            if durdt.year != 0 or durdt.month != 0:
                # create Duration
                ret = Duration(days=durdt.day, seconds=durdt.second,
                               microseconds=durdt.microsecond,
                               minutes=durdt.minute, hours=durdt.hour,
                               months=durdt.month, years=durdt.year)
            else:  # FIXME: currently not possible in alternative format
                # create timedelta
                ret = timedelta(days=durdt.day, seconds=durdt.second,
                                microseconds=durdt.microsecond,
                                minutes=durdt.minute, hours=durdt.hour)
            return ret
        raise ISO8601Error("Unable to parse duration string %r" % datestring)
    groups = match.groupdict()
    for key, val in groups.items():
        if key not in ('separator', 'sign'):
            if val is None:
                groups[key] = "0n"
            # print groups[key]

it does not check, whether only the last component has fractions.
        it allows weeks specified with all other combinations

      The alternative format does not support durations with years, months or
      days set to 0.
    """
    if not isinstance(datestring, basestring):
        raise TypeError("Expecting a string %r" % datestring)
    match = ISO8601_PERIOD_REGEX.match(datestring)
    if not match:
        # try alternative format:
        if datestring.startswith("P"):
            durdt = parse_datetime(datestring[1:])
            if durdt.year != 0 or durdt.month != 0:
                # create Duration
                ret = Duration(days=durdt.day, seconds=durdt.second,
                               microseconds=durdt.microsecond,
                               minutes=durdt.minute, hours=durdt.hour,
                               months=durdt.month, years=durdt.year)
            else:  # FIXME: currently not possible in alternative format
                # create timedelta
                ret = timedelta(days=durdt.day, seconds=durdt.second,
                                microseconds=durdt.microsecond,
                                minutes=durdt.minute, hours=durdt.hour)
            return ret
        raise ISO8601Error("Unable to parse duration string %r" % datestring)
    groups = match.groupdict()
    for key, val in groups.items():
        if key not in ('separator', 'sign'):
            if val is None:
                groups[key] = "0n"
            #print groups[key]