Stuck, again

trouble with result, i have to much spaces My result: "left, left, left, stop" And correct result "left,left,left,stop" but if remove them, next assert will be failed

My Code:

def left_join(phrases):
    """
        Join strings and replace "right" to "left"
    """
    import re
    phrase=str(phrases)
    phrase=re.sub('[\'()]','',phrase)
    return phrase.replace('right','left')

if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert left_join(("left", "right", "left", "stop")) == "left,left,left,stop", "All to left"
    assert left_join(("bright aright", "ok")) == "bleft aleft,ok", "Bright Left"
    assert left_join(("brightness wright",)) == "bleftness wleft", "One phrase"
    assert left_join(("enough", "jokes")) == "enough,jokes", "Nothing to replace"