class IsoDoc::I18n

def l10n_context(nodes, idx)

deal with spaces and empty text by just concatenating entire context
do not use just the immediately adjoining text tokens for context
previous, following context of current text node: 
def l10n_context(nodes, idx)
  prev = nodes[0...idx].map(&:text).join
  foll = nodes[(idx + 1)...(nodes.size)].map(&:text).join
  [prev, foll]
end