<gh_stars>1-10
# Python - 3.6.0

Test.assert_equals(update_light('green'), 'yellow')
Test.assert_equals(update_light('yellow'), 'red')
Test.assert_equals(update_light('red'), 'green')

# Python - 3.6.0

Test.assert_equals(update_light('green'), 'yellow')
Test.assert_equals(update_light('yellow'), 'red')
Test.assert_equals(update_light('red'), 'green')
# Python - 3.6.0