FindLabel Wildcard

Hi,

I'm new to writing label expressions and python and I was wondering whether there is a possibility to use wildcards in the Label-Expression-Window?
The problem is, I have different .gdbs with different field names, e.g. [SHAPE_Length] and [SHAPE.len] and I wanted to avoid writing mutliple expression files...
Is something like
def FindLabel [(SHAPE*insert-Wildcard-here*)]:
.
.
.
possible?

Thank you so much!!!