What the... The result of ?USE(1) isn't an illegal function call, but rather a blank string... Try it if you don't believe me!

I figured it out. PRINT(1) is just PRINT (1) 'the expression (1) which is the same as PRINT 1 So it's not a function, just a normal statement with an argument that is enclosed in parentheses. Like PRINT(X+1)*8