xml.a[0] === a_copy: false
a_copy.parent(): undefined
a_copy.toXMLString(): <a test="it">a</a>
a_copy.attributes(): it
a_copy.attributes()[0].parent(): a
a_copy.attributes()[0].parent() === a_copy true
///
xml.b[0] === b_copy: false
b_copy.parent(): undefined
b_copy.toXMLString(): <b><c>c1</c><c>c2</c></b>
b_copy.c[0].parent(): <b><c>c1</c><c>c2</c></b>
b_copy.c[0].parent() === b_copy: true
///
xml.b.c === c_copy: false
c_copy.toXMLString(): <c>c1</c>
<c>c2</c>
c_copy[0].parent(): undefined
c_copy[1].parent(): undefined
c_copy[0][0] c1
c_copy[0][0] === xml.b.c[0][0] false
