# Install virtualenv for Python 2.7 and create a sandbox called my27project:

pip2. install virtualenv

virtualenv-2.7 my27project

# Use the built-in pyvenv program in Python 3.3 to create a sandbox called my33project:

pyvenv-3.3 my33project

# Check the system Python interpreter version:

python --version

# This will show Python 2.6.

# Activate the my27project sandbox and check the version of the default Python interpreter in it:

source my27project/bin/activate

python --version

# This will show Python 2.7.

deactivate

# Activate the my33project sandbox and check the version of the default Python interpreter in it:

source my33project/bin/activate

python --version

# This will show Python 3.3.

deactivate