implemented reachability checking. passing 56 test cases locally

AST.py

@@ -68,28 +68,10 @@ class ASTNode():
             if c and hasattr(c, 'checkType'):
                 c.checkType()
 
-    def staticAnalysis(self):
-        for c in self.children:
-            if c and hasattr(c, 'staticAnalysis'):
-                c.staticAnalysis()
-
-    # return outMaybe
-    def reachCheck(self, inMaybe = True):
-        if inMaybe == False:
-            # error if in[s] = no for any s
-            # I don't think it should get to here... but maybe?
-            raise Exception("in[s] = no for a certain {}".format(type(self)))
-    
-        self.inMaybe = inMaybe
-        self.outMaybe = self.inMaybe
-        lastOut = self.inMaybe
-
+    def reachCheck(self, inMaybe=True):
         for c in self.children:
             if c and hasattr(c, 'reachCheck'):
-                lastOut = c.reachCheck(lastOut)
-                self.outMaybe = self.outMaybe and lastOut
-
-        return self.outMaybe
+                c.reachCheck(inMaybe)
 
     def printNodePretty(self, prefix=0):
         pp = pprint.PrettyPrinter(indent=prefix)