How to translate VBScript to Python-parser in Field Calculator

Question

How do I translate the following VBScript code in Label Expression to Python using the Python-parser?

Function FindLabel ( [MHUNIT], [BLDG_NUM] )
 If Not IsNull( [MHUNIT] ) Then
  FindLabel = [MHUNIT]
 Else
  FindLabel = [BLDG_NUM]
 End If
End Function

Answer 1

This should do what you want:

def FindLabel([MHUNIT], [BLDG_NUM]):
    if [MHUNIT]:
        return [MHUNIT]
    else:
        return [BLDG_NUM]