def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def image_thumbnail(filename):
    filepath = os.path.join(app.config.get('UPLOAD_FOLDER'), filename)
    im = Image.open(filepath)
    w, h = im.size

    if w > h:
        im.thumbnail((106, 106*h/w))
    else:
        im.thumbnail((106*w/h, 106))

    im.save(os.path.join(app.config.get('UPLOAD_FOLDER'), 
        os.path.splitext(filename)[0] + '_thumbnail' + os.path.splitext(filename)[1]))