def level_10(num):
    """Return the next number in the 'see-and-say' sequence, given a number.
    
    The next number in the sequence is found by saying the count of each digit,
    in order, in the current number.
    """
    # ensure the input is a number as a string
    num_as_str = str(num)
    
    count = 0
    current_digit = num_as_str[0]
    next_num_as_str = ''

    for digit in num_as_str:
        if digit == current_digit:
            count += 1
        else:
            next_num_as_str += '{}{}'.format(count, current_digit)
            count = 1
            current_digit = digit
    else:
        next_num_as_str += '{}{}'.format(count, current_digit)
    
    return next_num_as_str