Who was Marcus's guest in the episode when Rufus's guest was Rory McGrath?
CREATE TABLE table_23442 (
    "Episode" text,
    "First broadcast" text,
    "Rufus guest" text,
    "Marcus guest" text,
    "Winner" text
)
SELECT "Marcus guest" FROM table_23442 WHERE "Rufus guest" = 'Rory McGrath'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Who was Marcus's guest in the episode when Rufus's guest was Rory McGrath? ### Input: CREATE TABLE table_23442 (
    "Episode" text,
    "First broadcast" text,
    "Rufus guest" text,
    "Marcus guest" text,
    "Winner" text
) ### Response: SELECT "Marcus guest" FROM table_23442 WHERE "Rufus guest" = 'Rory McGrath'