def birth_before_death(gedcom):
    """
        validationg that individuals birthday is before individuals death.
    """
    result = []
    for individual in gedcom.individuals:
        birth = individual.birthday
        death = individual.death
        
        if death == None:
            continue
        elif death < birth:
            result.append(f'Error: US03: The individual {individual.name} ({individual.id}) has death before birth, death = {individual.death}, birth = {individual.birthday}')
    
    return result