added async block to codegen.h
added async block to codegen.h

gabrielPeart/Tranquil,gabrielPeart/Tranquil,fjolnir/Tranquil,gabrielPeart/Tranquil,fjolnir/Tranquil,gabrielPeart/Tranquil,fjolnir/Tranquil,gabrielPeart/Tranquil,fjolnir/Tranquil,gabrielPeart/Tranquil,fjolnir/Tranquil,fjolnir/Tranquil