[]=

Sets an element, replacing any previous matching element. If no existing element is found ,the element is added.

index

Used to find a matching element to replace. See []().

element

The element to replace the existing element with the previous element

Returns

nil if no previous element was found.

doc = Document.new '<a/>'
doc.root.elements[10] = Element.new('b')    #-> <a><b/></a>
doc.root.elements[1]                        #-> <b/>
doc.root.elements[1] = Element.new('c')     #-> <a><c/></a>
doc.root.elements['c'] = Element.new('d')   #-> <a><d/></a>