'Return the LLVM IR for all signatures encountered thus far, or the LLVM
IR for a specific signature if given.'

def inspect_llvm(self, signature=None):

    if (signature is not None):
        return self.definitions[signature].inspect_llvm()
    else:
        return dict(((sig, defn.inspect_llvm()) for (sig, defn) in self.definitions.items()))
