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:**

Difficulty: introductory

Starter code:

def make_sentences(parts):
	

Solutions:
def make_sentences(parts):
    return ' '.join(parts).replace(' ,', ',').strip(' .') + '.'

import re

def make_sentences(parts):
    return re.sub(' ([,.])', r'\1', ' '.join(parts).replace(' ,', ',')).rstrip('.') + '.'

import re

def make_sentences(parts):
    return re.match(r'[^\.]+', ' '.join(parts).replace(' , ', ', ')).group().strip() + '.'

def make_sentences(parts):
    result = ''
    for i in range(len(parts) - 1):
        result += parts[i]
        if parts[i + 1] not in '.,':
            result += ' '
    result += parts[-1]
    return result.rstrip('.') + '.'

def make_sentences(parts):
    return ' '.join(x for x in parts if x != '.').replace(' ,',',') + '.'

def make_sentences(parts):
    return ' '.join(parts).replace(' ,', ',').rstrip(' .') + '.'

def make_sentences(parts):
    import re
    sentence = re.sub(r'\b ([.,])', r'\1', ' '.join(parts)).rstrip('. ')
    return sentence + '.'

def make_sentences(parts):
    return '{}.'.format(
        ''.join(' ' + a if a.isalnum() else a for a in parts).strip(' .'))


def make_sentences(parts):
    n = ''
    parts = [i for i in parts if i != '.']
    for i in parts:
        if i == ',':
            n = n[:-1] + ', '
        else:
            n += i + ' '
    return n[:-1]+'.'