How to use the rpcq.messages.ParameterSpec function in rpcq

def _collect_memory_descriptors(program: Program) -> Dict[str, ParameterSpec]:
    """Collect Declare instructions that are important for building the patch table.

    This is secretly stored on BinaryExecutableResponse. We're careful to make sure
    these objects are json serializable.

    :return: A dictionary of variable names to specs about the declared region.
    """
    return {
        instr.name: ParameterSpec(type=instr.memory_type, length=instr.memory_size)
        for instr in program
        if isinstance(instr, Declare)
    }