2 cirles cannot be cut by 'Trim with regions' command

Grasshopper: I am trying to trim 2 circles (marked with blue colour) with the line (marked with violet).
However the ‘trim with regions’ commend is orange and there is a message that ‘Only closed trimming regions ought to be used’.
I don’t know what it means. And I have no idea how to trim those circles.
I tried to use the ‘optional solution plane’ but with no result.
Any ideas? I attach my Grasshopper definition and a few print screens to explain the problem.

E3_03 trim with regions.gh (29.4 KB)

Closed regions literally means periodic curve or polyline with boundary area, not linear curve or section profile.
You’ll probably know what i mean if you check the attachment.

E3_03 trim with regions_re.gh (31.8 KB)

Thank you very much :smile: