code: function obsAddrList() {
          return opts.strict ? null : wrap('obs-addr-list', and(
              star(and(
                  invis(opt(cfws)),
                  literal(',')
              )),
              address,
              star(and(
                  literal(','),
                  opt(and(
                      address,
                      invis(cfws)
                  ))
              ))
          )());
      }
docs: obs-addr-list   =   *([CFWS] ",") address *("," [address / CFWS])