When I use the Python ast package to get the functions of Python files, I find the functions defined in the body of `if` statement cannot be recognized.

Here is my code:
with open(py_file, 'r') as f:
    data = f.read()
    module = ast.parse(data)
    func_def = [node for node in module.body if isinstance(node, ast.FunctionDef)]

Here is an example of Python file:
if supports_bytes_environ:
    def _check_bytes(value):
        if not isinstance(value, bytes):
            raise TypeError("bytes expected, not %s" % type(value).__name__)
        return value

The function `_check_bytes` is not in `func_def`. I also tested `ast.iter_child_nodes(module)` and it also has this issue.