class Kramdown::Converter::Pdf

def block_hash(opts)

from the given options.
Helper function that returns a hash with valid options for the prawn #text_box extracted 
def block_hash(opts)
  hash = {}
  [:align, :valign, :mode, :final_gap, :leading, :fallback_fonts,
   :direction, :indent_paragraphs].each do |key|
    hash[key] = opts[key] if opts.has_key?(key)
  end
  hash
end