Plaster

CL-USER> (let ((hash-table (make-hash-table))) (push 42 (gethash :foo hash-table '(1 2 3))) (gethash :foo hash-table)) (42 1 2 3) T CL-USER> (let ((hash-table (make-hash-table))) (incf (gethash :foo hash-table 0)) (gethash :foo hash-table)) 1 T