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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def FlowManager(start_string, end_string):
 """ A factory for creating context managers for standard code constructions, such as if statements and functions. :param str start_string: A format string for the beginning of this code structure :param str end_string: A format string for the end of this code structure The constructor of the returned class takes as arguments a `CodeWriter` instance followed by keyword arguments that will be used to format `start_string` and `end_string` """

    class Inner(object):
        def __init__(self, f, **kwargs):
            self.f = f
            self.kwargs = kwargs

        def __enter__(self):
            self.f.writeln(start_string.format(**self.kwargs))
            self.f.indent()

        def __exit__(self, type, value, traceback):
            self.f.deindent()
            self.f.writeln(end_string.format(**self.kwargs))
    return Inner