parseTime.py

from datetime import timedelta
import re


def parseTime(s):
    m = re.match(r'^(\d+) *([a-z]+)$', s)
    if m is None:
        raise ValueError("couldn't parse time string")
    units = 'seconds minutes hours days weeks'.split()
    num = float(m[1])
    for unit in units:
        if unit.startswith(m[2]):
           break
    else:
        raise ValueError(f'Unknown unit {m[2]}')
    return timedelta(**{unit: num})


print(parseTime('1d'))
print(parseTime('5m'))