Alternative syntax for blocks with decorator and context manager

Created originally on Bitbucket by paugier (Pierre Augier)

I'd like to support such things:

for functions:

from transonic import with_blocks, block

@with_blocks
def func(arg: int):
    a = non_pythranizable(arg)
    with block():
        a: float
        tmp = a + arg
    return non_pythranizable(tmp)

I think supporting return in a block is going to be difficult.

for classes:

from transonic import boost, with_blocks, block

@boost
class MyClass:
    attr0: int

    @with_blocks
    def func(self, arg: int):
        a = non_pythranizable(arg)
        with block():
            a: float
            tmp = a + arg + self.attr0
        return non_pythranizable(tmp)

• We could also support block signatures # transonic block (int: a, b; A: c, d, e) in the block.