def putkeep (k, v)

      k = k.to_s; v = v.to_s

      @db.putkeep(k, v)
    end
def putkeep (k, v)

      k = k.to_s; v = v.to_s

      @db.putkeep(k, v)
    end
Like #put but doesn't overwrite the value if already set. Returns true
 only if there no previous entry for k.