Python dictionary supports intersection and union operations

d=dict(a=1,b=2,c=3)
k=d.keys()    #dict_keys(['a', 'b', 'c'])
 del d[ 'a' ]
 print (k)     #k will dynamically change dict_keys(['b', 'c' ])
 #The key of the dictionary is unique, supports intersection and union operations, d.values() is not allowed
 print (k|{ 'x' : 4 })     #{'c', 'b', 'x '}
 print (k&{ 'x' : 4 })     #set()
 print (d.items()|{ 'x' : 4 })     #{'x', ('b', 2), ('c ', 3)}
 print (d.items()&{ 'x' :4})    #set()
print(d.values()|{'x':
4})   #报错TypeError: unsupported operand type(s) for |: 'dict_values' and 'dict'