def word_combine(x):
    """ Returns a string that combines a list of words with proper commas and trailing 'and' """
    num_words = len(x)
    if num_words == 1: return x[0]

    combined = ""
    i = 1
    for item in x:
        if i == num_words:
            combined += "and " + item
            break

        if (num_words == 2 and i == 1):
            combined += item + " "
        else:
            combined += item + ", "

        i+=1
    
    return combined