implicit_plot plot of a list

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Hello,

On Sage 8.5, Release Date: 2018-12-22, I am doing

var('x,y')

F1 =plot([k/x for k in [-5..5]], (-5, 5), ymin=-5, ymax = 5, detect_poles=True, color="red")

F2= implicit_plot([y^2 - x^2 -c for c in [-5..5]], (x,-5,5), (y,-5,5))

to obtain two families of orthogonal curves. While the first family is ok, there seems to be a problem with the second one.

I can circunvent my problem by doing a lis of plots (instead of the plot of a list), as follows :

[implicit_plot(y^2 - x^2 -c ==0, (x,-5,5), (y,-5,5), color="blue" ) for c in [-5..5]]

I was expecting that plot(...) and implicit_plot(...) would beheave in the same manner in this situation. Why this is not the case? Am I missing something in the syntax?

Regards, JC