docs: def tzabbr_register(abbr, name, region, zone, dst):
    """Register a new timezone abbreviation in the global registry.
  
    If another abbreviation with the same name has already been registered it new
    abbreviation will only be registered in region specific dictionary.
    """
    newabbr = tzabbr()
    newabbr.abbr = abbr
    newabbr.name = name
    newabbr.region = region
    newabbr.zone = zone
    newabbr.dst = dst
  
    if abbr not in all:
      all[abbr] = newabbr
  
    if not region in regions:
      regions[region] = {}
  
    assert abbr not in regions[region]
    regions[region][abbr] = newabbr