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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_assign_annotation(node):
 """Get the type annotation of the assignment of the given node. :param node: The node to get the annotation for. :type node: astroid.nodes.Assign or astroid.nodes.AnnAssign :returns: The type annotation as a string, or None if one does not exist. :type: str or None """

    annotation = None

    annotation_node = None
    try:
        annotation_node = node.annotation
    except AttributeError:
        # Python 2 has no support for type annotations, so use getattr
        annotation_node = getattr(node, "type_annotation", None)

    if annotation_node:
        if isinstance(annotation_node, astroid.nodes.Const):
            annotation = node.value
        else:
            annotation = annotation_node.as_string()

    return annotation