old_contents: export default function parseTimeString(str) {
      const regexRes = new RegExp('[0-9]{0,2}:[0-9]{0,2}').exec(str);
      let hours = null;
      let minutes = null;
      if (regexRes) {
          const parts = regexRes[0].split(':');
  
          hours = parseInt(parts[0], 10) || 0;
          minutes = parseInt(parts[1], 10) || 0;
      }
  
      return {
          hours,
          minutes,
      };
  }
  
new_contents: const TIME_STRING_REGEX = /([0-9]{0,2}):([0-9]{0,2})/;
  
  export default function parseTimeString(str) {
      const regexRes = TIME_STRING_REGEX.exec(str);
      let hours = null;
      let minutes = null;
  
      if (regexRes) {
          hours = parseInt(regexRes[1], 10) || 0;
          minutes = parseInt(regexRes[2], 10) || 0;
      }
  
      return {
          hours,
          minutes,
      };
  }
  
subject: Use regex for parsing TimeString