Be careful not to built-in functions in Python or the property assignment
Use del *** to delete, restore its default properties
[() And,] is a tuple
[[]] Is a list
{{}} Is a dictionary
Selected portion, as a parameter passed into dict
This is the same
Write about this key is not quoted
Direct index, if the key does not exist and will directly create a key assignment added to the dictionary, if the key exists, corresponding to the key value will be modified.