Controlling an Arduino with Python

[cubangt]

yea so i watched a few videos this weekend on firmata and think i understand now..So the videos i watched showed how to setup everything and it seems that the only thing once the firmata sketch was loaded on the uno, the rest of the code was writting within python on the guys computer and he was sending/executing commands from his .py file to set pins high and low.. and never once did he upload another sketch..

Is that correct to say that once you load the basic firmata sketch onto the board, the code and logic can all be done within the python file/script and run it from there since you already have the serial com setup and communicating?