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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 add_comment(node, text, location='above'):
 """Add a comment to the given node. If the `SourceWithCommentGenerator` class is used these comments will be output as part of the source code. Note that a node can only contain one comment. Subsequent calls to `add_comment` will ovverride the existing comments. Args: node: The AST node whose containing statement will be commented. text: A comment string. location: Where the comment should appear. Valid values are 'above', 'below' and 'right' Returns: The node with the comment stored as an annotation. """

  anno.setanno(node, 'comment', dict(location=location, text=text), safe=False)
  return node