code: def get_tz(tz) -> str:
      
      from xbbg.const import exch_info
  
      if tz is None: return DEFAULT_TZ
  
      to_tz = tz
      if isinstance(tz, str):
          if hasattr(TimeZone, tz):
              to_tz = getattr(TimeZone, tz)
          else:
              exch = exch_info(ticker=tz)
              if 'tz' in exch.index:
                  to_tz = exch.tz
  
      return to_tz
docs: Convert tz from ticker / shorthands to timezone
  
      Args:
          tz: ticker or timezone shorthands
  
      Returns:
          str: Python timzone
  
      Examples:
          >>> get_tz('NY')
          'America/New_York'
          >>> get_tz(TimeZone.NY)
          'America/New_York'
          >>> get_tz('BHP AU Equity')
          'Australia/Sydney'