user: Question: What round has Hereford United as the opponent?
Columns: ['Date', 'Round', 'Opponent', 'Venue', 'Result', 'Attendance']
Types: ['text', 'text', 'text', 'text', 'text', 'real']
Sample row: ['5 Jan', 'Three', 'Chasetown', 'A', 'W 3 - 1', 2420.0]
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Opponent" = 'Hereford United';