When rating to certain countries with USPS International (try Taiwan as an example), an exception is generated:

ERROR:karrio.api.interface:time data '3 - 5 business days to many major markets' does not match format '%m/%d/%Y'
Traceback (most recent call last):
  File "/home/me/karrioship/karrio/sdk/core/karrio/api/interface.py", line 62, in wrapper
    return func(*args, **kwargs)
  File "/home/me/karrioship/karrio/sdk/core/karrio/api/interface.py", line 301, in deserialize
    return gateway.mapper.parse_rate_response(response)
  File "/home/me/karrioship/karrio/sdk/extensions/usps_international/karrio/mappers/usps_international/mapper.py", line 102, in parse_rate_response
    return parse_rate_response(response.deserialize(), self.settings)
  File "/home/me/karrioship/karrio/sdk/extensions/usps_international/karrio/providers/usps_international/rate.py", line 23, in parse_rate_response
    quotes: typing.List[models.RateDetails] = [
  File "/home/me/karrioship/karrio/sdk/extensions/usps_international/karrio/providers/usps_international/rate.py", line 24, in <listcomp>
    _extract_details(package, settings)
  File "/home/me/karrioship/karrio/sdk/extensions/usps_international/karrio/providers/usps_international/rate.py", line 35, in _extract_details
    delivery_date = lib.to_date(postage.GuaranteeAvailability, "%m/%d/%Y")
  File "/home/me/karrioship/karrio/sdk/core/karrio/lib.py", line 176, in to_date
    return utils.DF.date(
  File "/home/me/karrioship/karrio/sdk/core/karrio/core/utils/datetime.py", line 31, in date
    return datetime.strptime(str(date_value), current_format)
  File "/usr/lib/python3.9/_strptime.py", line 568, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
  File "/usr/lib/python3.9/_strptime.py", line 349, in _strptime
    raise ValueError("time data %r does not match format %r" %
ValueError: time data '3 - 5 business days to many major markets' does not match format '%m/%d/%Y'

This is because the GuaranteeAvailability field is being mapped to a date in rate.py like:

delivery_date = lib.to_date(postage.GuaranteeAvailability, "%m/%d/%Y")

But according to the USPS documentation:

If an estimated scheduled delivery date is available, the format will beMM/DD/YYYYe.g.,01/29/2014. If an estimated scheduled delivery date is not available, the format will be a String.e.g.,3 - 5 business days to many major markets

So rate.py needs to be adjusted to either keep it just as a string, or detect if USPS is returning a date and if so, use the date, otherwise keep it a string.