The 7th day of the Little Turtle Python 28 episode because I know you so forever

set Set # No mapping case, there is a mapping to a dictionary.
Create a Collection
1.set1=set ([1,2,3,3]) #重复直接剔除
2.{} #set是无序的
immutable set : Frozen frozen, frozen Frozenset

1 num3 = Frozenset ([2-in-a-  num3 = {3  -Num3.add (4   4  Error

Open

' R ' opens the file as read-only
' W ' opens the file as written, overwriting the existing file
' x ' If the file already exists, open with this mode throws an exception
' A ' opens in write mode, append write at end If file already exists
' B ' to open files in binary mode
' t ' opens in text mode (default)
' + ' read-write mode (can be added to other modes for use)
' U ' universal line break support

The 7th day of the Little Turtle Python 28 episode because I know you so forever