S9 LIB  (run* (variable) query)  ==>  list
        (run* () query)          ==>  list

Run the given AMK (Another Micro Kanren) query and return its
result, if any. See the book "Logic Programming in Scheme"
(http://www.t3x.org/nmh/book-pdfs/) for an introduction to AMK.
If a variable is given, return all values for that variable
that satisfy the query.

(run* (vq) (appendo vq (_) '(a b c)))
  ==>  (() (a) (a b) (a b c))
