multifab is an object that constructs new contracts by copying
code from existing contracts with EXTCODECOPY. It is inspired
by an old idea, now
motivated by a real use case: Vyper doesn't have factories!
multifab has two functions:
function cache(bytes calldata code) external returns (bytes32 codehash);
Call cache with some contract code to make multifab deploy a dummy version and return its codehash.
Now you can call build with that codehash.
function build(bytes32 codehash, bytes calldata args) external returns (address made) {
Call build with a codehash (must have been cached prior) and arguments, get back the address of a new instance of that contract built with those constructor arguments.