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All the following expressions are like Greek and Latin to me.

Now I understand how patients must be feeling when I'm trying to explain to them about medical terminology

condexpr definition

An expression that returns a numeric result. If the result is zero then the conditional is False. If the result is non-zero then the conditional is True.

0 'false 
-1 'true 
X > 20 'true if X is greater than 20 
S$ = "hello" 'true if S$ equals "hello"