Database: superhero (difficulty: simple)
Question: Give the race of the Indigo-haired male superhero.
SQL: SELECT T3.race FROM superhero AS T1 INNER JOIN colour AS T2 ON T1.hair_colour_id = T2.id INNER JOIN race AS T3 ON T1.race_id = T3.id INNER JOIN gender AS T4 ON T1.gender_id = T4.id WHERE T2.colour = 'Indigo' AND T4.gender = 'Male'