user: Question: what builder launched 20 Jun 1953?
Columns: ['Ship', 'Original Pennant Number', 'Builder', 'Laid Down', 'Launched', 'Commissioned']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['HMCSChaleur(MCB 144)', 'MCB 144', 'Port Arthur Shipbuilding , Port Arthur', '8 Jun 1951', '21 Jun 1952', '18 Jun 1954']
SQL:

assistant: SELECT "Builder" FROM "Table" WHERE "Launched" = '20 Jun 1953';