I wish I could do:

```
 let myFun param1 param2 = 
      .....
      if condition 1
          ....
          if condition 2
               yield ....

 let sequence = seq { for x in xs do
                            myFun 1 x
                            myFun 2 x
                    }

```

But now I can only do

```
 let myFun param = 
      .....
      .....
      if condition 1
          ....
          if condition 2
               Some....
          else None    // has to complete else
      else None

 let sequence = seq { for x in xs do
                        match myFun 1 x with
                        | Some x -> yield x
                        | None   -> ()
                        match myFun 2 x with
                        | Some x -> yield x
                        | None   -> ()
                    }

  let sequence2 =  // order will be different, and we can not have index passed into function unless we do a futher Seq.map

       let a = xs |> Seq.choose (myFun 1)
       let b = xs |> Seq.choose (myFun 2)
       Seq.append a b

```

My real code:

The code looks not that good a few `None` and I tried `Seq.choose`, which is not that helpful since it doesn't support `Seq.choosei`.

```
        let exam isForward brickID =
            let brick = state.[brickID]
            let (nextTR, nextOccupied, nextUnoccupied) = if isForward then brick.Body.nudgeForward () else brick.Body.nudgeBack ()
            if (nextOccupied.isInGrid gridSize) && (map.ContainsKey nextOccupied |> not) then
                let nextBrick = { brick with Body = nextTR }
                let nextState = getNextState state brickID nextBrick
                if not (explored.Contains nextState) then
                    let nextMap = map |> Map.remove nextUnoccupied
                                      |> Map.add nextOccupied nextBrick
                    Some ((nextState, nextMap), (nextBrick, if isForward then brick.Body.Direction else brick.Body.Direction.Opposite))
                else None
            else None

        seq { for brickID in 0 .. state.Length - 1 do
                match exam true brickID with
                | Some x -> yield x
                | None   -> ()
                match exam false brickID with
                | Some x -> yield x
                | None   -> ()
        }

```