How do I save functions to individual files in PostgreSQL?

Question

I maintain a legacy application that uses a PostgreSQL database.

The application is heavily dependent on stored procedures (aka functions).

I want to save these functions to files named after the function name so I can then use a VCS (version control system).

I know that I can save the code with the ALTER FUNCTION using PgAdmin but this only allows me to save one function at a time.

I am looking for a way to save all the functions automatically. Is there any way to script this task?