run python script from terminal with imports code example

Example 1: run python.py file

# save a file in text editor with .py
# open terminal, and change directories
# run the following command:
python3 file.py

Example 2: to run python script in terminal i want to type python insted of python3

$ python --version
Python 2.7.6
$ python3 --version
Python 3.4.3
$ alias python=python3
$ python --version
Python 3.4.3