set-or-create-cell! for docjure

docjure.clj

(defn   set-or-create-cell! 
  ([sheet n val type]
    (let [cellref (org.apache.poi.ss.util.CellReference. n)
          r (.getRow cellref)
          col (int (.getCol cellref))
          row (or (.getRow sheet r) (.createRow sheet r))
          cell (or (select-cell n sheet) (.createCell row col type))]
      (set-cell! cell val)))
  ([sheet n val]
    (set-or-create-cell! sheet n val org.apache.poi.ss.usermodel.Cell/CELL_TYPE_STRING)))