Nesting 'WITH' statements in Python

AFAIK you can't read a file open with append mode 'a'.

I found the solution in python's doc. You may want to have a look at this (Python 3) or this (Python 2)

If you are running python 2.7+ you can use it like this:

with open(file1) as fsock1, open(file2, 'a') as fsock2:
    fstring1 = fsock1.read()
    fstring2 = fsock2.read()

This way you avoid unnecessary indentation.