I can ceate several plots like this
a = plot_vector_field(field1, (x,-1,2), (z,-1,2))
b = plot_vector_field(field2, (x,-1,2), (z,-1,2))
c = plot_vector_field(field3, (x,-1,2), (z,-1,2))
and merge them with
show(a+b+c)
How can I save the resulting image?
show(a+b+c).save('pic.pdf')
does not work.