Parsed test spec with 3 sessions

starting permutation: s2rx s2ry s1ry s1wy s1c s3r s2wx s2c s3c
step s2rx: SELECT balance FROM bank_account WHERE id = 'X';
balance        

0              
step s2ry: SELECT balance FROM bank_account WHERE id = 'Y';
balance        

0              
step s1ry: SELECT balance FROM bank_account WHERE id = 'Y';
balance        

0              
step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y';
step s1c: COMMIT;
step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id;
id             balance        

X              0              
Y              20             
step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X';
step s2c: COMMIT;
step s3c: COMMIT;