I do not understand why you mention PCASL_3D. The part of your code that you have modified isn't about folderHiererachy but about session tokens. Session tokens can be only ASL_1 or ASL_3 or ASL_13 etc. But never PCASL_3D, unless somebody writes nonsense to sourcestructure.json.

Also - I do not understand why you mention last folder layers in the issue. The changes you made apply to sessions and not folderHierarchy.

I agree with the code changes, just want to clarify the issue etc. Or have I overlooked something??

Haha think about it. If you search for any ASL_3, there is an occurrence in PC ASL_3 D ;)

I do not understand why you mention PCASL_3D. The part of your code that you have modified isn't about folderHiererachy but about session tokens. Session tokens can be only ASL_1 or ASL_3 or ASL_13 etc. But never PCASL_3D, unless somebody writes nonsense to sourcestructure.json.
Also - I do not understand why you mention last folder layers in the issue. The changes you made apply to sessions and not folderHierarchy.
I agree with the code changes, just want to clarify the issue etc. Or have I overlooked something??

Haha think about it. If you search for any ASL_3, there is an occurrence in PC ASL_3 D ;)

Yes. I am thinking about it :) It's a list of sessions, not folderHierarchy. The values can be only ASL_1 or ASL_2 etc. Where would PCASL_3D come from in that list? We are talking about a list of sessions here, not about folder names. If I get it right.

Also - check my other comments.

I do not understand why you mention PCASL_3D. The part of your code that you have modified isn't about folderHiererachy but about session tokens. Session tokens can be only ASL_1 or ASL_3 or ASL_13 etc. But never PCASL_3D, unless somebody writes nonsense to sourcestructure.json.
Also - I do not understand why you mention last folder layers in the issue. The changes you made apply to sessions and not folderHierarchy.
I agree with the code changes, just want to clarify the issue etc. Or have I overlooked something??

Haha think about it. If you search for any ASL_3, there is an occurrence in PC ASL_3 D ;)

Yes. I am thinking about it :) It's a list of sessions, not folderHierarchy. The values can be only ASL_1 or ASL_2 etc. Where would PCASL_3D come from in that list? We are talking about a list of sessions here, not about folder names. If I get it right.

Also - check my other comments.

What the code did: was checking for ANY occurrence of ASL_\d+ and taking the first instance, which would detect /Siemens_PCASL_3D_Test/sourcedata/sub-001/ASL_1 as ASL_3 (from PCASL_3D).

I improved this now in two ways:

1. ensuring it searches for ASL_d+.nii
2. taking the last index only

You're right that (2) is not really necessary anymore, I just kept it there to be sure.