code to generate graph paper

pl1 := plot({seq([[i,-10],[i,10]],i=-10..10),
seq([[-10,i ],[10,i]],i=-10..10)}, color=blue):
pl2 := plot({[[0,-10],[0,10]],[[-10,0],[10,0]]},
color=blue,thickness=3):
pl3 := plot({seq([[5*i,-10],[5*i,10]],i=[-1,1]),
seq([[-10,5*i ],[10,5*i]],i=[-1,1])}, color=blue,thickness=2):
pap :=plots[display]([pl3,pl1,pl2],axes=none,
scaling=constrained):
pap;

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