def lix_calc(sentences):
    """
    Calculate LIX, assuming that all tokens are actual words, not punctuation or delimiters.

    >>> print("%.2f" % lix_calc(4*["a bc def ghij klmno pqrstu vxyzåäö".split()]))
    21.29
    """
    sentence_counter = 0.0
    word_counter = 0.0
    length_counter = 0.0
    for words in sentences:
        sentence_counter += 1
        for word in words:
            word_counter += 1
            length_counter += int(len(word) > 6)
    if word_counter == 0 and sentence_counter == 0:
        return float('NaN')
    elif word_counter == 0 or sentence_counter == 0:
        return float('inf')
    else:
        return word_counter / sentence_counter + 100 * length_counter / word_counter