def encode_tick_rule_array(tick_rule_array: list) ->str:
    """
    Encode array of tick signs (-1, 1, 0)

    :param tick_rule_array: (list) of tick rules
    :return: (str) encoded message
    """
    message = ''
    for element in tick_rule_array:
        if element == 1:
            message += 'a'
        elif element == -1:
            message += 'b'
        elif element == 0:
            message += 'c'
        else:
            raise ValueError('Unknown value for tick rule: {}'.format(element))
    return message
