The window of the chosen data flow

This Internet can search a lot:

Simple example:

#!/usr/bin/env pythonimport os.pathf = open( os.path.join( os.path.abspath("."), "A.pkl"),"w")f.write("1")f.close()f = open( os.path.join( os.path.abspath("."), "A.pkl:legend"),"w")f.write("2")f.close()f = open( os.path.join( os.path.abspath("."), "A.pkl:legend1"),"w")f.write("3")f.close()f = open( os.path.join( os.path.abspath("."), "A.pkl"),"r")S = f.read()print(S)f.close()f = open( os.path.join( os.path.abspath("."), "A.pkl:legend"),"r")S = f.read()print(S)f.close()

Print out:

1

2

Note: If A.pkl is written last, the result will clear this alternative data stream