code: function character(options = {}) {
    let chars = options.chars || ['-', '*', '+'];
  
    if (typeof chars === 'string') {
      return fill(...chars.split('..'), options);
    }
  
    return chars;
  }
docs: Create the array of characters to use as bullets.
  
  - http://spec.commonmark.org/0.19/#list-items
  - https://daringfireball.net/projects/markdown/syntax#list
  - https://help.github.com/articles/markdown-basics/#lists
  
  @param  {Object} `opts` Options to pass to [fill-range][]
  @return {Array}