I"m learning python, and I'm trying to do this, which I thought should be trivial, but apparently, it's not.

$python
>>> def isTrue(data):
...     "ping" in data
... 
>>> if isTrue("ping"):
...     print("pong")       >>>>>>>>>>>>>> shouldn't this print "pong"???
... 
>>>

You actually need to return the value. Then, it will work.

>>> def isTrue(data):
...     return "ping" in data
... 
>>> if isTrue("ping"):
...     print("pong")
...
pong
>>>