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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _diff_group_position(group):
 """Generate a unified diff position line for a diff group"""

    old_start = group[0][0]
    new_start = group[0][1]
    old_length = new_length = 0
    for old_line, new_line, line_or_conflict in group:
        if isinstance(line_or_conflict, tuple):
            old, new = line_or_conflict
            old_length += len(old)
            new_length += len(new)
        else:
            old_length += 1
            new_length += 1
    if old_length:
        old_start += 1
    if new_length:
        new_start += 1

    return color.LineNumber('@@ -%s,%s +%s,%s @@' % (old_start, old_length, new_start, new_length))