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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 make_images_responsive(app, doctree):
 """ Add Bootstrap img-responsive class to images. """


    for fig in doctree.traverse(condition=nodes.figure):
        if 'thumbnail' in fig['classes']:
            continue

        for img in fig.traverse(condition=nodes.image):
            img['classes'].append('img-responsive')