def make_sentences(parts):
    output = ""

    for x in parts:
        if x == ",":
            output+=x
        elif x != ".":
            output+=" {}".format(x)

    return "{}{}".format(output[1:],".")

'''
Implement a function, so it will produce a sentence out of the given parts.

Array of parts could contain:

    words;
    commas in the middle;
    multiple periods at the end.

Sentence making rules:

    there must always be a space between words;
    there must not be a space between a comma and word on the left;
    there must always be one and only one period at the end of a sentence.

Example:

makeSentence(['hello', ',', 'my', 'dear']) // returns 'hello, my dear.'
'''
