preprocessing stage and macro evaluation stage

[ethers]

develop 8236410

This is for reference, as possible improvement to future Serpent version.

preprocessing stage happens before macro evaluation stage, so code like the following doesn't work:

macro m():
    # (sha3(1, chars=48):uint256)  by itself this works
    x=1
    (sha3(x, chars=48):uint256)

def foo():
    return (m())

Invalid argument count or LLL function: (kv (~sha3 (get 'x) 48) (get 'uint256))