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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 attrs(self, attribute_name):
 """ Retrieve HTML attribute values from the elements matched by the query. Example usage: .. code:: python # Assume that the query matches html elements: # <div class="foo"> and <div class="bar"> >> q.attrs('class') ['foo', 'bar'] Args: attribute_name (str):
 The name of the attribute values to retrieve. Returns: A list of attribute values for `attribute_name`. """

        desc = u'attrs({!r})'.format(attribute_name)
        return self.map(lambda el: el.get_attribute(attribute_name), desc).results