Optional Parameter in User Function.

[StephenG1CMZ]

Not in the current product, but I understand this is possible in the beta release.
Currently, one workaround is to use lists:

Outline only:
Export feet(LST)
If size(LST) ==1...LST(1)
IF SIZE(LST)== 2...LST(1)+LST(2)
Call: feet({5}) or feet({5,6}