Added shorter hand closure syntax as follows:

{|x y z| ...}
where x, y, and z are parameters and ... is the body of the closure.

{...}
where there is no parameter list declaration and ... is the body of the
closure.

{| |}
where there is no parameter list declaration and ... is the body of the
closure. Corresponds to:
{null}

Signed-off-by: Jakob Brandsborg Ehmsen <jakobehmsen.github@gmail.com>