sloonz

  check()
    .then()

  > check()
  undefined
  > .then()
  Invalid REPL keyword

  check().
    then()

  check()
    .then(result => {
      if (result) {
         // set state to finished
      }
      check()
        .then(result => {
          if (result) {
              // set state to finished
          }
          check()
            .then(result => {
              if (result) {
                 // set state to finished
              }
              check()
                .then(result => {
                  if (result) {
                    // set state to finished
                  }
                  check()
                    .then(result => {
                      if (result) {
                         // set state to finished
                      }

                      // set state to not done
                    })
                    .catch(error =>  // set state to failed);
                })
                .catch(error =>  // set state to failed);
            })
            .catch(error =>  // set state to failed);
        })
        .catch(error =>  // set state to failed);
    })
    .catch(error =>  // set state to failed);

  const resultOrNull = await Promise.resolve(null).
       then(result => result || check()).
       then(result => result || check()).
       then(result => result || check()).
       then(result => result || check()).
       then(result => result || check()).
       catch(error => null);