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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 get_docstring(node):
 """ Return the docstring for the given node or `None` if no docstring can be found. If the node provided does not accept docstrings a `TypeError` will be raised. """

    if not isinstance(node, (FunctionDef, ClassDef, Module)):
        raise TypeError("%r can't have docstrings" % node.__class__.__name__)
    if node.body and isinstance(node.body[0], Str):
        return node.body[0].s