doc = ADocument.objects.create()
c1 = doc.commit(description="Commit A1", text=text_a1)
c2 = doc.commit(description="Commit A2", text=text_a2, parent=c1)
doc = ADocument.objects.create()
c1 = doc.commit(description="Commit A1", text=text_a1)
c2 = doc.commit(description="Commit A2", text=text_a2, parent=c1)