code: function(source, format, ctx) {
    if (inputFormats.hasOwnProperty(format)) {
      return inputFormats[format](source, ctx);
    } else {
      throw new Error('invalid format to make a text block from: ' + source.format);
    }
  }
docs: Make a text block from source
  @param {String} source The source to make a text block from
  @param {String} format The format to use
  @param {Object} ctx An object to be passed to all of the rendering functions
  @return {Object} a new textblock