1. Upon starting, PiSH shall output two dashes.
2. Upon needing input, PiSH shall output a dot.
3. Upon receiving an invalid command, PiSH shall output two dots.
4. Upon receiving a valid command and beginning execution, PiSH shall output a dash.
5. Upon the failure of a command, two dots shall be outputted.
6. Upon the sucess of a command, a dash shall be outputted.
7. After a command has either failed or completed, PiSH will wait for one second before awaiting input again.
8. Built-in commands shall be:
   - exit - return to the OS
   - morse STRING - transmit STRING in Morse code
   - exec CMD [ARGS] - execute the shell command CMD with the arguments ARGS in the current working directory
   - cd PATH - change the current working directory to PATH
   - pwd - transmit the current working directory in Morse code
9. Upon receiving ANY signal, PiSH shall output two dashes and exit.