'a' in d: True d['a']: va 'b' in d: True d['b']: vb 'c' in d: True d['c']: vc 'd' in d: True d['d']: vd 'a' in d: False 'b' in d: True d['b']: vb 'c' in d: True d['c']: vc 'd' in d: True d['d']: vd 'e' in d: True d['e']: ve 'b' in d: True d['b']: vb2 'c' in d: True d['c']: vc2 'd' in d: True d['d']: vd 'e' in d: False 'f' in d: True d['f']: vf 'b' in d: False 'c' in d: False 'd' in d: False 'e' in d: False 'f' in d: False 'a' in d: True d['a']: 1 'b' in d: True d['b']: 2