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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 mobile_template(template):
 """ Mark a function as mobile-ready and pass a mobile template if MOBILE. For example:: @mobile_template('a/{mobile/}b.html') def view(template=None):
 if ``request.MOBILE=True`` the template will be `a/mobile/b.html`. if ``request.MOBILE=False`` the template will be `a/b.html`. This function is useful if the mobile view uses the same context but a different template. """

    def decorator(f):
        @functools.wraps(f)
        def wrapper(*args, **kwargs):
            ctx = stack.top
            if ctx is not None and hasattr(ctx, 'request'):
                request = ctx.request
                is_mobile = getattr(request, 'MOBILE', None)
                kwargs['template'] = re.sub(r'{(.+?)}',
                                            r'\1' if is_mobile else '',
                                            template)
            return f(*args, **kwargs)
        return wrapper
    return decorator