Dict-Set?

(dict-set? dictionary key) -> boolean

Checks to see if key is one of the keys in dictionary. Returns true if it is, otherwise false.

Examples:

>>(define a (dict '(alpha 1) '(beta 2) '(gamma 3)))
:: #f
>>(dict-set? a 'alpha)
:: #t
>>(dict-set? a 'delta)
:: #f