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 delete_lines(self, min_row, max_row):
        if min_row == -1:
            self.current_label.fuzz_values = self.current_label.fuzz_values[:-1]
        else:
            self.current_label.fuzz_values = self.current_label.fuzz_values[:min_row] + self.current_label.fuzz_values[
                                                                                        max_row + 1:]

        _ = self.current_label  # if user deleted all, this will restore a fuzz value

        self.fuzz_table_model.update()