26.3 FromIterator

[njr0]

This is a bit trivial, but the code in 26.2 doesn't print anything. So I suppose running it shows that it doesn't produce an error, but it's a bit underwhelming.

I added

println!("{:?}", prime_squares);

at the end, which (more convincingly) printed

[4, 9, 25, 49]

[djmitche]

#1271