code: function fws() {
          return wrap('fws', or(
              obsFws,
              and(
                  opt(and(
                      star(wsp),
                      invis(crlf)
                     )),
                  star(wsp, 1)
              )
          )());
      }
docs: 3.2.2. Folding White Space and Comments FWS             =   ([*WSP CRLF] 1*WSP) /  obs-FWS