Without that, if Python allowed it, would it do given:
a = "xxx" test_dict = {a=3, b=2}
JS does the latter always, so the variable a is not related to the literal key a which is understood as an unquoted string "a":
> a = "xxx" 'xxx' > test_dict = {a:3, b:2} { a: 3, b: 2 } > test_dict["xxx"] undefined > test_dict["a"] 3
dict(1=5, 6=7, 7="aaa")
dict(hashableInstance="foo", anotherHashableInstance=23, (1,5)=8)
except Python syntax choices of course.
And if they wanted a string, they'd do it like:
dict("1"=5, 6=7, 7="aaa")