Read the contents of a file in python

//To read the entire contents  

with open("filename.txt") as f:
    contents = f.read()

//To read line by line 

#!/usr/bin/python

filename = "myfile.txt"
with open( filename ) as f:
    # file read can happen here
    # print "file exists"
    print f.readlines()

with open( filename, "w") as f:
    # print "file write happening here"
    f.write("write something here ")