<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_string(cfunc, *args):
 """ Call a C function and return its return value as a Python string. :param cfunc: C function to call :param args: Arguments to call function with :rtype: str """

    cstr = get_ctype("const char**", cfunc, *args)
    return backend.ffi.string(cstr).decode() if cstr else None