iter.py

class Reverse:
    """Creates an iterator that reverses the object constructed"""

    def __init__(self, data):
        """Usual constructor.  Note that in this case, we need to have
        a member variable that will maintain my state when implementing
        __next__for iteration."""
        self.data = data # Some iterable set of data
        self.index = len(data) # data better support the len operation

    def __iter__(self):
        """If an object is passed to for, whatever __iter__ returns
        is what will be used.  That returned object must have a
        __next__ method"""
        return self  # The class already has __next__, so good to go

    def __next__(self):
        """Implement the iteration behavior, including throwing an
        exception when we're done"""
        if self.index == 0: #Remember, going backward, so this is the last
            raise StopIteration
        self.index = self.index - 1 # Update state
        return self.data[self.index] # Return the latest iterated value from data


if __name__ == '__main__':
    for c in Reverse('Welcome to PyCharm'):
        print(c, end='')
    print()

# See PyCharm help at https://www.jetbrains.com/help/pycharm/