Ruler Demo

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0123456789
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          0123456789
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                    0123456789
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                              0123456789
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                                        0123456789
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                                                  0123456789
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0123456789
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          0123456789
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                    0123456789
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                              0123456789
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                                        0123456789
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                                                  0123456789
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0123456789
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          0123456789
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                    0123456789
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                              0123456789
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                                        0123456789
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                                                  0123456789
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Demonstration of the rulers addon, which displays vertical lines at given column offsets.