Clojurians Log v2

hey guys, maybe i am wrong, but look like s/if or s/cond-pre are used for specifiying if you datatype will be a map or vector or whatever. What i am looking for is a way to say that something will be a vector of vector and it could have inside it schema A or schema B or nil or or even three of them at the same time. Something like (s/defschema schema-name {:name s/Str :space s/if [[A B nil]] [[A nil]] [[B nil]] [[nil]]})

can anyone help me please?