[translation] Silence some C++ compile warnings

By changing Python code

cpp/embedded_file_gen.py

@@ -20,7 +20,7 @@ def main(argv):
 
   # Invoked with _devbuild/help/* stdlib/*.ysh 
 
-  log('paths %s', paths)
+  #log('paths %s', paths)
 
   out_f.write('''
 #include "cpp/embedded_file.h"

data_lang/j8.py

@@ -290,3 +290,4 @@ def Parse(self, s):
 
         """
         # TODO: feed it to lexer first, then parser
+        return None

frontend/typed_args.py

@@ -105,49 +105,48 @@ def __init__(self, pos_args, named_args):
 
     def Word(self):
         # type: () -> str
-        pass
+        return None  # TODO
 
     def RestWords(self):
         # type: () -> List[str]
-        pass
+        return None  # TODO
 
     ### Typed positional args
 
     # TODO: may need location info
     def PosStr(self):
         # type: () -> str
-        pass
+        return None  # TODO
 
     def PosInt(self):
         # type: () -> int
-        pass
+        return -1  # TODO
 
     def RestPos(self):
         # type: () -> List[value_t]
-        pass
+        return None  # TODO
 
     ### Typed named args
 
     def NamedStr(self, param_name, default_):
         # type: (str, str) -> str
-        pass
+        return None  # TODO
 
     def NamedInt(self, param_name, default_):
         # type: (str, int) -> int
-        pass
+        return -1  # TODO
 
     def RestNamed(self):
         # type: () -> Dict[str, value_t]
-        pass
+        return None  # TODO
 
     def Block(self):
         # type: () -> command_t
         """
         Block arg for proc
         """
-
         # TODO: is this BraceGroup?
-        pass
+        return None  # TODO
 
     def Done(self):
         # type: () -> None

ysh/expr_eval.py

@@ -182,6 +182,8 @@ def _EvalPlaceExpr(self, place):
             else:
                 raise NotImplementedError(place)
 
+        raise AssertionError()  # silence C++ compiler
+
     def EvalPlaceExpr(self, place):
         # type: (place_expr_t) -> lvalue_t
         """Public API for _EvalPlaceExpr to ensure command_sub_errexit"""
@@ -479,6 +481,8 @@ def _ArithNumeric(self, left, right, op):
             else:
                 raise error.InvalidType('Expected Int or Float', loc.Missing)
 
+        raise AssertionError()  # silence C++ compiler
+
     def _ArithDivideInt(self, left, right):
         # type: (value_t, value_t) -> value.Int
         left_i = self._ValueToInteger(left)
@@ -683,6 +687,8 @@ def _CompareNumeric(self, left, right, op):
                 raise error.InvalidType('Expected Int or Float operands',
                                         loc.Missing)
 
+        raise AssertionError()  # silence C++ compiler
+
     def _EvalCompare(self, node):
         # type: (expr.Compare) -> value_t