def preprocessData(data):
    """
    Clean up the data by replacing timestamps and IP addresses with unique
    tokens.

    GIVEN:
      data (list)       list of events

    RETURN:
      new_data (list)   copy of `data` with timestamps and IP addresses
                        cleaned up
    """
    new_data = data

    # Replace timestamps with '<<TIMESTAMP>>'
    # Replace IP addresses with '<<ATTACKER>>' or '<<DEFENDER>>'

    return new_data