How to use the gcovr.utils.calculate_coverage function in gcovr

def branch_coverage(self):
        # type: () -> Tuple[int, int, Optional[float]]
        total = 0
        cover = 0
        for line in self.lines.values():
            b_total, b_cover, _ = line.branch_coverage()
            total += b_total
            cover += b_cover

        percent = calculate_coverage(cover, total, nan_value=None)
        return total, cover, percent

def branch_coverage(self):
        # type: () -> Tuple[int, int, Optional[float]]
        total = len(self.branches)
        cover = 0
        for branch in self.branches.values():
            if branch.is_covered:
                cover += 1

        percent = calculate_coverage(cover, total, nan_value=None)
        return total, cover, percent

total, cover, percent = coverage.line_coverage()
            uncovered_lines = coverage.uncovered_lines_str()
        percent = '--' if percent is None else str(int(percent))
        return (total, cover,
                filename + str(total).rjust(8) + str(cover).rjust(8)
                + percent.rjust(6) + "%   " + uncovered_lines)

    for key in keys:
        (t, n, txt) = _summarize_file_coverage(covdata[key])
        total_lines += t
        total_covered += n
        OUTPUT.write(txt + '\n')

    # Footer & summary
    OUTPUT.write("-" * 78 + '\n')
    percent = calculate_coverage(total_covered, total_lines, nan_value=None)
    percent = "--" if percent is None else str(int(percent))
    OUTPUT.write(
        "TOTAL".ljust(40) + str(total_lines).rjust(8)
        + str(total_covered).rjust(8) + str(percent).rjust(6) + "%" + '\n'
    )
    OUTPUT.write("-" * 78 + '\n')

    # Close logfile
    if options.output:
        OUTPUT.close()

def line_coverage(self):
        # type: () -> Tuple[int, int, Optional[float]]
        total = 0
        cover = 0
        for line in self.lines.values():
            if line.is_covered or line.is_uncovered:
                total += 1
            if line.is_covered:
                cover += 1

        percent = calculate_coverage(cover, total, nan_value=None)
        return total, cover, percent