code: function ws_get_cell_stub(ws, R, C) {
  	/* A1 cell address */
  	if(typeof R == "string") return ws[R] || (ws[R] = {t:'z'});
  	/* cell address object */
  	if(typeof R != "number") return ws_get_cell_stub(ws, encode_cell(R));
  	/* R and C are 0-based indices */
  	return ws_get_cell_stub(ws, encode_cell({r:R,c:C||0}));
  }
docs: /* get cell, creating a stub if necessary