Experimenting and messing with Python (v2.7) source code, inspired by two blog posts, Replacing import with accio: A Dive into Bootstrapping and Python's Grammar and Python internals: adding a new statement to Python.

First step is to clone and install. Details as to why we need this intermediary version of Python can be read in this article

git clone [email protected]:dr4ke616/custom_python.git
cd intermediary_python/
./configure --with-pydebug
make clean && make -s -j2
cd bin/
export PATH=`pwd`:$PATH

Now we go to the my_python directory and install the new version

cd ../../my_python
./configure --with-pydebug
make clean && make -s -j2
cd bin/
export PATH=`pwd`:$PATH
cd ../../

We can test now with:

python test_custom_python.py

>>> print "hello"
  File "<stdin>", line 1
    print 'hello'
                ^
SyntaxError: invalid syntax

>>> shout 'hello'
hello

Checkout test_custom_python.py for some more examples