Grease Pencil : Wave on a string line

Hello
Using Grease Pencil
Starting with a straight line (drawn or with endpoints)
I would like to know how to animate a straight line, that is creating a wave. Like on a flat water, a wave that moves and propagate itself up and down along the horizon line. like wave on the ocean.
can I Interpolate, create a Sequence ( Sinusoidal ) ?
Thank you for you to explain if you know how to animate to vibrate a string or propagate a wave.
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Martin