user: Question: Name the formed that has type of 4-COR
Columns: ['Units', 'Type', 'Period used', 'Formed from', 'Trailers']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['601', '6-TC', '1965–1967', 'COR/PAN/PUL cars', 'TTK/TCK/TTK/TTK']
SQL:

assistant: SELECT "Formed from" FROM "Table" WHERE "Type" = '4-COR';