takes the same arguments as spec/keys and returns a regex op that matches sequences of key/values,
converts them into a map, and conforms that map with a corresponding
spec/keys call:
user=> (s/conform (s/keys :req-un [::a ::c]) {:a 1 :c 2})
{:a 1, :c 2}
user=> (s/conform (s/keys* :req-un [::a ::c]) [:a 1 :c 2])
{:a 1, :c 2}
the resulting regex op can be composed into a larger regex:
user=> (s/conform (s/cat :i1 integer? :m (s/keys* :req-un [::a ::c]) :i2 integer?) [42 :a 1 :c 2 :d 4 99])
{:i1 42, :m {:a 1, :c 2, :d 4}, :i2 99}