code: function listHandler(string, selectionRange, type) {
    const start = startOfLine(string, selectionRange[0]);
    const end = endOfLine(string, selectionRange[1]);
    const lines = splitLines(string.substring(start, end));
    const boundaryRegex = /[~*`_[!]|[a-zA-Z]|\r|\n|$/gm;
    const newLines = [];
  
    lines.forEach((line, i) => {
      const symbol = type === 'ul' ? '- ' : `${i + 1}. `;
      let newLine;
  
      // If the line begins with an existing list symbol
      if (indexOfMatch(line, /^[0-9#>-]/m, 0) === 0) {
        const existingSymbol = line.substring(0, 0 + line.substring(0).search(boundaryRegex));
  
        // Remove the symbol
        newLine = line.substring(line.search(boundaryRegex), line.length);
        if (existingSymbol.trim() !== symbol.trim()) {
          newLine = symbol + line.substring(line.search(boundaryRegex), line.length);
        }
        return newLines.push(newLine);
      }
      newLine = symbol + line.substring(0, line.length);
      return newLines.push(newLine);
    });
  
    // Put it all together
    const joined = newLines.join('\r\n');
    const value = string.substring(0, start) + newLines.join('\r\n') + string.substring(end, string.length);
    return { value, range: [start, start + joined.replace(/\n/gm, '').length] };
  }
docs: Handles adding/removing format strings to groups of lines
  @param   {String} string  the entire string to use
  @param   {Number[]}  selectionRange the starting and ending positions of the selection
  @param   {String} type    ul or ol
  @returns {Object} the new string, the updated selectionRange