Tests fail on Python 3.9: NotImplementedError: Advanced Slicing not supported
```py
_____________________________________________________________________________________________________________________ test_bubble_sort _____________________________________________________________________________________________________________________

    def test_bubble_sort():
        source = parse(
            "def sort(seq):",
            "    L = len(seq)",
            "    for _ in range(L):",
            "        for n in range(1, L):",
            "            if seq[n] < seq[n - 1]:",
            "                seq[n - 1], seq[n] = seq[n], seq[n - 1]",
            "    return seq",
        )
>       cpp = transpile(source)

py14/tests/test_transpiler.py:166:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
py14/transpiler.py:37: in transpile
    cpp = transpiler.visit(tree)
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py14/transpiler.py:273: in visit_Module
    buf = [self.visit(b) for b in node.body]
py14/transpiler.py:273: in <listcomp>
    buf = [self.visit(b) for b in node.body]
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py14/transpiler.py:87: in visit_FunctionDef
    body = "\n".join([self.visit(n) for n in node.body])
py14/transpiler.py:87: in <listcomp>
    body = "\n".join([self.visit(n) for n in node.body])
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py14/transpiler.py:168: in visit_For
    buf.extend([self.visit(c) for c in node.body])
py14/transpiler.py:168: in <listcomp>
    buf.extend([self.visit(c) for c in node.body])
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py14/transpiler.py:168: in visit_For
    buf.extend([self.visit(c) for c in node.body])
py14/transpiler.py:168: in <listcomp>
    buf.extend([self.visit(c) for c in node.body])
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py14/transpiler.py:239: in visit_If
    if self.visit(node.test) == '__name__ == std::string {"__main__"}':
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
py2many/clike.py:133: in visit_Compare
    left = self.visit(node.left)
py2many/clike.py:61: in visit
    return super(CLikeTranspiler, self).visit(node)
/usr/local/Cellar/python@3.9/3.9.2_2/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ast.py:407: in visit
    return visitor(node)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <py14.transpiler.CppTranspiler object at 0x10c05c970>, node = <ast.Subscript object at 0x10c05c040>

    def visit_Subscript(self, node):
        if isinstance(node.slice, ast.Ellipsis):
            raise NotImplementedError("Ellipsis not supported")

        if not isinstance(node.slice, ast.Index):
>           raise NotImplementedError("Advanced Slicing not supported")
E           NotImplementedError: Advanced Slicing not supported

py14/transpiler.py:305: NotImplementedError
```