old_contents: export default function indent(amount, string) {
    if (!amount) {
      return string;
    }
  
    let ind = ' ';
    for (let index = 1; index < amount; index++) {
      ind += ' ';
    }
  
    return ind + string.split('\n').join('\n' + ind);
  }
  
new_contents: const mapper = ind => line => {
    if (line === '') {
      return '';
    }
    return ind + line;
  };
  
  export default function indent(amount, string) {
    if (!amount) {
      return string;
    }
  
    let ind = ' ';
    for (let index = 1; index < amount; index++) {
      ind += ' ';
    }
  
    return string.split('\n').map(mapper(ind)).join('\n');
  }
  
subject: fix empty line indent error