Pytronics is a Python library that allows you control the Rascal hardware, like digital pins and serial ports. The code reference lists the available functions, while this tutorial gives basic usage examples. If you need more detail, you can also read the Pytronics source code itself.
Most of the pins on the Rascal are digital, meaning that they can switch back and forth between 3.3 V and 0 V, but can't linger in between. There are also 4 special analog pins that can read voltages in between 3.3 V and 0 V. (There are no pins on the Rascal that are analog outputs, but something like the Adafruit audio shield might work.)
Each pin has a name. The list of legal names and their location on the Rascal can be found on the pinout page.
There are two functions for controlling digital pins. You need to pass each function a pin name in quotes so it knows which pin you want to affect.
set_pin_high()
set_pin_low()
Here are a couple of examples:
from pytronics import *
set_pin_high('2') # This makes pin 2 output 3.3 V.
set_pin_low('11') # This makes pin 11 output 0 V.
The Rascal has 3 serial ports.
send_serial(text, speed=19200, port='1')
The function send_serial() defaults to 19200 bps on port 1 (pins 0 and 1). You can pass it speed and port parameters if you want to transmit at a different speed or on a different port.
This code doesn't actually exist yet. In the meantime, you can use the Python subprocess module and the command line tools i2cget and i2cset to fake it.