code: def unindent_tree(element):
      
      for el in element.iter():
          if is_indentation_element(el):
              el.attrib.clear()
              el.tag = 'div'
              return
docs: Removes the outermost indent. For example, the tree
      "<div>A<blockqote>B<div>C<blockquote>D</blockquote>E</div>F</blockquote>G</div>"
      is transformed to
      "<div>A<div>B<div>C<blockquote>D</blockquote>E</div>F</div>G</div>"