Invalid python function name fix (#69)

* fix macOS barvinok build

* fix invalid python function name

* special casing for invalid py identifier

gen_wrap.py

@@ -412,6 +412,11 @@ def on_directive_handle(self, directive, toks, ifpassthru, precedingtoks):
 # {{{ FunctionData (includes parser)
 
 class FunctionData:
+
+    INVALID_PY_IDENTIFIER_RENAMING_MAP = {
+        "2exp": "two_exp"
+    }
+
     def __init__(self, include_dirs):
         self.classes_to_methods = {}
         self.include_dirs = include_dirs
@@ -656,6 +661,13 @@ def parse_decl(self, decl):
         if name in PYTHON_RESERVED_WORDS:
             name = name + "_"
 
+        name = self.INVALID_PY_IDENTIFIER_RENAMING_MAP.get(name, name)
+
+        if name[0].isdigit():
+            print(f"SKIP: {class_name} {name} "
+                   "(unhandled invalid python identifier)")
+            return
+
         if class_name == "options":
             assert name.startswith("set_") or name.startswith("get_"), (name, c_name)
             name = f"{name[:4]}option_{name[4:]}"