old_contents: """
  exception definitions
  """
  
  
  class AprsParseError(Exception):
      """Parse error while parsing an aprs packet."""
      def __init__(self, aprs_string):
          self.message = "This is not a valid APRS string: %s" % aprs_string
          super(AprsParseError, self).__init__(self.message)
          self.aprs_string = aprs_string
  
  
  class OgnParseError(Exception):
      """Parse error while parsing an aprs packet substring"""
      def __init__(self, substring, expected_type):
          self.message = "For type %s this is not a valid token: %s" % (expected_type, substring)
          super(OgnParseError, self).__init__(self.message)
          self.substring = substring
          self.expected_type = expected_type
  
new_contents: """
  exception definitions
  """
  from datetime import datetime
  
  
  class AprsParseError(Exception):
      """Parse error while parsing an aprs packet."""
      def __init__(self, aprs_string):
          self.aprs_string = aprs_string
  
          self.message = "This is not a valid APRS string: {}".format(aprs_string)
          super(AprsParseError, self).__init__(self.message)
  
  
  class OgnParseError(Exception):
      """Parse error while parsing an aprs packet substring."""
      def __init__(self, substring, expected_type):
          self.substring = substring
          self.expected_type = expected_type
  
          self.message = "For type {} this is not a valid token: {}".format(expected_type, substring)
          super(OgnParseError, self).__init__(self.message)
  
  
  class AmbigousTimeError(Exception):
      """Timstamp from the past/future, can't fully reconstruct datetime from timestamp."""
      def __init__(self, reference, packet_time):
          self.reference = reference
          self.packet_time = packet_time
          self.timedelta = reference - datetime.combine(reference, packet_time)
  
          self.message = "Can't reconstruct timstamp, {:.0f}s from past.".format(self.timedelta.total_seconds())
          super(AmbigousTimeError, self).__init__(self.message)
  
subject: Add user-defined exception AmbigousTimeError