docs: def zero_year_special_case(from_date, to_date, start, end):
      """strptime does not resolve a 0000 year, we must handle this."""
  
      if start == 'pos' and end == 'pos':
          # always interval from earlier to later
          if from_date.startswith('0000') and not to_date.startswith('0000'):
              return True
          # always interval from later to earlier
          if not from_date.startswith('0000') and to_date.startswith('0000'):
              return False
          # an interval from 0000-MM-DD/0000-MM-DD ??? PARSE !!!
          if from_date.startswith('0000') and to_date.startswith('0000'):
              # fill from date assuming first subsequent date object if missing
              # missing m+d, assume jan 1
              if len(from_date) == 4:
                  fm, fd = 1, 1
              # missing d, assume the 1st
              elif len(from_date) == 7:
                  fm, fd = int(from_date[5:7]), 1
              # not missing any date objects
              elif len(from_date) == 10:
                  fm, fd = int(from_date[5:7]), int(from_date[8:10])
              # fill to date assuming first subsequent date object if missing
              # missing m+d, assume jan 1
              if len(to_date) == 4:
                  tm, td = 1, 1
              # missing d, assume the 1st
              elif len(to_date) == 7:
                  tm, td = int(to_date[5:7]), 1
              # not missing any date objects
              elif len(to_date) == 10:
                  tm, td = int(to_date[5:7]), int(to_date[8:10])
              # equality check
              if from_date == to_date:
                  return True
              # compare the dates
              if fm <= tm:
                  if fd <= td:
                      return True
                  else:
                      return False
              else:
                  return False
      # these cases are always one way or the other
      # "-0000" is an invalid edtf
      elif start == 'neg' and end == 'neg':
          return False
      # False unless start is not "0000"
      elif start == 'neg' and end == 'pos':
          if from_date.startswith("0000"):
              return False
          else:
              return True