Implementing a python-xpp interpreter

[markolenik]

The future plan for this package is to go beyond importing ICs or parameters, but to also access and evaluate custom functions in xpp. The Python AST module might make that possible. Here's example of defining and evaluating a function:

function_string = 'func = lambda x: x**2'
syntax = ast.parse(function_string)
xpp_dict = {}
exec(compile(code, filename="", mode="exec"), None, xpp_dict)
print(xpp_dict['func'](2))

>> Out[1]: 4

I see here two options to getting the xpp functions into Python:

1. Use the already implemented syntax and write it to strings that can be read by Python.
2. Convert my syntax to ast objects (see https://docs.python.org/3/library/ast.html).