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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def choose_plural(amount, variants):
 """ Choose proper case depending on amount @param amount: amount of objects @type amount: C{integer types} @param variants: variants (forms) of object in such form: (1 object, 2 objects, 5 objects). @type variants: 3-element C{sequence} of C{unicode} or C{unicode} (three variants with delimeter ',') @return: proper variant @rtype: C{unicode} @raise ValueError: variants' length lesser than 3 """

    
    if isinstance(variants, six.text_type):
        variants = split_values(variants)
    check_length(variants, 3)
    amount = abs(amount)
    
    if amount % 10 == 1 and amount % 100 != 11:
        variant = 0
    elif amount % 10 >= 2 and amount % 10 <= 4 and \
         (amount % 100 < 10 or amount % 100 >= 20):
        variant = 1
    else:
        variant = 2
    
    return variants[variant]