def easy_string(length=10, repeatable=True, chars='23469cdfghjkmnpqrtvwxy'):
    '''Returns a string with specific characters.

    Mainly used to make sure the string doesn't contain characters that can
    be easily confused such as the number 0 and letter o

    NOTE do I need to make this unicode safe?
    '''
    choice = random.choice
    output = None
    if repeatable:
        output = (choice(chars) for i in range(length))
    else:
        output = []
        last_char = None
        current_char = None
        for i in range(length):
            added = False
            while not added:
                current_char = choice(chars)
                if current_char is None or current_char != last_char:
                    output.append(current_char)
                    last_char = current_char
                    added = True
    return ''.join(output).upper()