human
I am working on the file "Presentation.ipynb".
The first task is:
...and we can read the source code of built-in functions by downloading the source from the Python.org Mercurial repositories): https://hg.python.org/
Can you write Python program for it?

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Can you provide a the Python program you requested?
assistant
#Here is the Python program you requested.

# import inspect
# inspect.getsourcefile(range) # doesn't work for built-in functions

# Python's built-in "Counter" class defines the control flow of iterators,
# used in functions such as "for i in range(0,10) ..."

class Counter(object):
    def __init__(self, low, high):
        self.current = low
        self.high = high

    def __iter__(self):
        'Returns itself as an iterator object'
        return self

    def __next__(self):
        'Returns the next value till current is lower than high'
        if self.current > self.high:
            raise StopIteration
        else:
            self.current += 1
            return self.current - 1