How to add a new user defined function?

Question: How to add a new user defined function?

Answer: Follow these steps:

Library changes:

• Define a function class extending FunctionExpr in rapidnet-functions.h/cc Make sure it is generic by taking in arguments of type Expression wherever possible.
• Write test cases in rapidnet/tests/functions-test.cc

Compiler changes:

• Update the function LookupFunction() to map the function name to be used in the NDlog program to its class name in the Library.