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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def tree(self, expand=False, level=None):
 """Provide a ``print``-able display of the hierarchy. Parameters expand : bool, optional Only relevant for HTML representation. If True, tree will be fully expanded. level : int, optional Maximum depth to descend into hierarchy. Examples -------- / ├── bar │ ├── baz │ └── quux │ └── baz (100,) float64 └── foo / ├── bar │ ├── baz │ └── quux └── foo bar ├── baz └── quux └── baz (100,) float64 Notes ----- Please note that this is an experimental feature. The behaviour of this function is still evolving and the default output and/or parameters may change in future versions. """


        return TreeViewer(self, expand=expand, level=level)