Up to 3pi in ticks but only 2pi in labels #350
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I honestly don't know if this per purpose, but I was a little confused. Before there were four ticks but only three tick labels. If this was correct please forgive me for this PR.
Another solution (again if it was a typo before)
plot!(xticks = ([0:π:3*π;], ["0", "\\pi", "2\\pi, 3\\pi"]))