class REXML::Element

def previous_element


d.root.elements['b'].previous_element #-> nil
d.root.elements['c'].previous_element #->
d = REXML::Document.new 'text'

+niL+ otherwise:
Returns the previous sibling that is an element if it exists,

previous_element
:call-seq: 
def previous_element
  element = previous_sibling
  element = element.previous_sibling until element.nil? or element.kind_of? Element
  return element
end