How to get the head of SymFunction in SymEngine.jl

I define a symfunction as

Then I define some functions
The output is so called Basic type. I can get args conveniently by get_args(f1). But how can I get the head character “p” of f1 for example?
Thanks a lot.
By the way, does anybody know when does the symEngine can have solver functions? I am quite like to using symEngine as the amazing calculation speed. It will be quite nice if the developers can add the solve functions in it like SymPy.