plot a phase portrait

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How can we plot the phase portait?

I got a system of two differential equations:

$$ du/dt = u(1-u-0.2v) $$

$$ dv/dt = v(1-v-0.5u) $$

For a vector field:

var('u v')
plot_vector_field([u*(1-u-0.2*v),v*(1-v-0.5*u)],[u,0,2],[v,0,2])