code: function removeNewlineBetween(firstToken, secondToken) {
           const textRange = [ firstToken.range[1], secondToken.range[0] ],
                 textBetween = sourceCode.text.slice(textRange[0], textRange[1]);
  
           // Don't do a fix if there is a comment between the tokens
           if (textBetween.trim()) {
              return null;
           }
           return (fixer) => fixer.replaceTextRange(textRange, ' ');
        }
docs: -------------------------------------------------------------------------- Helpers -------------------------------------------------------------------------- 
  Fixes a place where a newline unexpectedly appears
  @param {Token} firstToken The token before the unexpected newline
  @param {Token} secondToken The token after the unexpected newline
  @returns {Function} A fixer function to remove the newlines between the tokens