Progressbar in Python
As per my comments, I've not sure SE.CodeReview is the right place to get the help you are looking for.

However, as I didn't read your question properly at first, I had a look at your code and changed a few things (please note that it's not exactly the same behavior as it used to be):


extract the display logic in a method on its own
reuse update in start and finish (little changes here : this method now updates the object instead of just doing some display)
removed self._seen because it didn't seem useful


Here the code :

class Progress(object):
    def __init__(self, maxval):
        self._pct = 0
        self.maxval = maxval

    def update(self, value):
        pct = int((value / self.maxval) * 100.0)
        if self._pct != pct:
            self._pct = pct
            self.display()

    def start(self):
        self.update(0)

    def finish(self):
        self.update(self.maxval)

    def display(self):
        sys.stdout.write("|%-100s| %d%%" % (u"\u2588"*self._pct, self._pct) + '\n')
        sys.stdout.flush()