code: def _parse_tzstr(self, tzstr, zero_as_utc=True):
      if tzstr == b"Z" or tzstr == b"z":
          return tz.UTC
  
      if len(tzstr) not in {3, 5, 6}:
          raise ValueError(
              "Time zone offset must be 1, 3, 5 or 6 characters"
          )
  
      if tzstr[0:1] == b"-":
          mult = -1
      elif tzstr[0:1] == b"+":
          mult = 1
      else:
          raise ValueError("Time zone offset requires sign")
  
      hours = int(tzstr[1:3])
      if len(tzstr) == 3:
          minutes = 0
      else:
          minutes = int(
              tzstr[(4 if tzstr[3:4] == self._TIME_SEP else 3) :]
          )
  
      if zero_as_utc and hours == 0 and minutes == 0:
          return tz.UTC
      else:
          if minutes > 59:
              raise ValueError("Invalid minutes in time zone offset")
  
          if hours > 23:
              raise ValueError("Invalid hours in time zone offset")
  
          return tz.tzoffset(None, mult * (hours * 60 + minutes) * 60)
  
file_path: catboost/contrib/python/python-dateutil/py3/dateutil/parser/isoparser.py
imports: from datetime import datetime, timedelta, time, date
  import calendar
  from dateutil import tz
  from functools import wraps
  import re
  import six
label_desc: Use image node_id 11 for calling the isoparser obj's underlying member method code with example usage: obj._parse_tzstr(tzstr, zero_as_utc) and returns: tz, tz, tz