How to use the f90nml.patch function in f90nml

def test_comment_patch(self):
        nml = {'comment_nml': {'v_cmt_inline': 456}}
        try:
            f90nml.patch('comment.nml', nml, 'tmp.nml')
            self.assert_file_equal('comment_patch.nml', 'tmp.nml')
        finally:
            os.remove('tmp.nml')

def test_repatch(self):
        f90nml.patch('repatch.nml', self.repatch_nml, 'tmp.nml')
        test_nml = f90nml.read('tmp.nml')
        try:
            self.assertEqual(test_nml, self.repatch_nml)
        finally:
            os.remove('tmp.nml')

def test_patch_paths(self):
        patch_nml = f90nml.read('types_patch.nml')
        f90nml.patch('types.nml', patch_nml, 'tmp.nml')
        test_nml = f90nml.read('tmp.nml')
        try:
            self.assertEqual(test_nml, patch_nml)
        finally:
            os.remove('tmp.nml')

def test_patch_files(self):
        patch_nml = f90nml.read('types_patch.nml')
        with open('types.nml') as f_in:
            with open('tmp.nml', 'w') as f_out:
                f90nml.patch(f_in, patch_nml, f_out)
                self.assertFalse(f_in.closed)
                self.assertFalse(f_out.closed)
        try:
            test_nml = f90nml.read('tmp.nml')
            self.assertEqual(test_nml, patch_nml)
        finally:
            os.remove('tmp.nml')

def test_default_patch(self):
        patch_nml = f90nml.read('types_patch.nml')
        f90nml.patch('types.nml', patch_nml)
        test_nml = f90nml.read('types.nml~')
        try:
            self.assertEqual(test_nml, patch_nml)
        finally:
            os.remove('types.nml~')

        # The above behavior is only for paths, not files
        with open('types.nml') as nml_file:
            self.assertRaises(ValueError, f90nml.patch, nml_file, patch_nml)

def test_patch_null(self):
        try:
            f90nml.patch('types.nml', {}, 'tmp.nml')
            self.assert_file_equal('types.nml', 'tmp.nml')
        finally:
            os.remove('tmp.nml')

grp = args.group

        update_nml_str = '&{0} {1} /\n'.format(grp, ', '.join(args.variable))
        update_io = StringIO(update_nml_str)
        update_nml = f90nml.read(update_io)
        update_io.close()

    # Target output
    output_file = open(output_fname, 'w') if output_fname else sys.stdout

    if args.patch:
        # We have to read the file twice for a patch.  The main reason is
        # to identify the default group, in case this is not provided.
        # It could be avoided if a group is provided, but logically that could
        # a mess that I do not want to sort out right now.
        f90nml.patch(input_fname, update_nml, output_file)

    else:
        # Update the input namelist directly
        if update_nml:
            try:
                input_data[grp].update(update_nml[grp])
            except KeyError:
                input_data[grp] = update_nml[grp]

        # Write to output
        if not args.patch:
            if output_fmt in ('json', 'yaml'):
                if output_fmt == 'json':
                    input_data = input_data.todict(complex_tuple=True)
                    json.dump(input_data, output_file,
                              indent=4, separators=(',', ': '))

def patch_namelist(orig_nml_path: str,patch_nml_path: str,new_nml_path: str):
    """This function updates a larger orginal namelist with a file containing a smaller subset of
    changes and writes out a new namelist to a file.
    Args:
        orig_nml_path: Path to the namelist file to be updated
        patch_nml_path: Path to the file containing the namelist updates
        new_nml_path: Path to write the new namelist file with updates applied.

    Returns:
        None
    """
    # Read in namelist patch
    patch_nml = f90nml.read(nml_path=patch_nml_path)

    # Write new namelist to file
    f90nml.patch(nml_path=orig_nml_path,
                 nml_patch=patch_nml,
                 out_path=new_nml_path)

    #print('New namelist written to ' + new_nml_path)
    return(None)