 associated values are the package objects
              themselves.
        :param columns: a tuple containing information about how to
           format the columns of output.  The absolute value of each
           number in the tuple indicates how much space has been
           allocated for the corresponding column.  If the number is
           negative, the text in the column will be left justified,
           and if it is positive, the text will be right justified.
           The columns of output are the package name, version, and
           repository
        :param highlight_modes: dictionary containing information
              about to highlight the packages in *highlight_na*.
              *highlight_modes* should contain the following keys::

                 'not_in' - highlighting used for packages not in *highlight_na*
                 '=' - highlighting used when the package versions are equal
                 '<' - highlighting used when the package has a lower version
                       number
                 '>' - highlighting used when the package has a higher version
                       number
        :return: number of packages listed
        r