I can use a FEEL expression as input value

[saig0]

Description

I am unable to perform the following unary test on the FEEL playground:
input: duration("PT36H")
unary test: (duration("P1D")..duration("P2D"))

I want to check if a given duration is in the range of two other durations. I cannot get the input into a format that is accepted by the libraries. "... is not valid JSON"
I cannot only use the string "PT36H", because it cannot be compared to a duration, of course.