q = region_plot(lambda x, y: x^2 - y^2 > 0, (-1, 1), (-1, 1), \
             incol='green', bordercol='gray', borderstyle='dashed', \
             aspect_ratio=1, alpha=0.3)
p1 = region_plot(lambda x, y: x-y > 0, (-1, 1), (-1, 1), \
             incol='red', bordercol='gray', borderstyle='dashed', \
             aspect_ratio=1, alpha=0.3)
p2 = region_plot(lambda x, y: x+y > 0, (-1, 1), (-1, 1), \
             incol='blue', bordercol='gray', borderstyle='dashed', \
             aspect_ratio=1, alpha=0.3)
p = p1 + p2

f = [p1,p2,p,q]
for _ in f:
    _.show()