[Haskell-beginners] fmap composition

[Marco Turchetto]

I'm reading the "Haskell programming" book and in chapter 16 about functors
they combine two "fmap" with the "(.)" function.
I really don't understand how the type of "fmap . fmap" is "(Functor f2,
Functor f1) => (a -> b) -> f1 (f2 a) -> f1 (f2 b)".

The thing that really freaks me out is that I thought that "(.)" arguments
are ONLY two unary function.
Maybe there is some curring magic underline, there is someone that can
explain to me how the type of "fmap . fmap" is derived from the type of
"fmap" and "(.)"?
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