def open type, file, *ps, &exe
			ps.push ::Hash.new  unless ::Hash === ps.last
			ps.last[:env] = self
			(type || SBDB::Unkown).new file, *ps, &exe
		end
def open type, file, *ps, &exe
			ps.push ::Hash.new  unless ::Hash === ps.last
			ps.last[:env] = self
			(type || SBDB::Unkown).new file, *ps, &exe
		end
Opens a Database.
 see SBDB::DB, SBDB::Btree, SBDB::Hash, SBDB::Recno, SBDB::Queue