text: function solve(arr = []) {
  
      let guests = [];
      
      for (let i = 0; i < arr.length; i++) {
  
        let tokens = arr[i].split(' ');
        if (guests.includes(tokens[0])) {
  
          tokens[2] === 'going!' ? console.log(`${tokens[0]} is already in the list!`) : guests = guests.filter(g => g !== tokens[0]);
        } else {
          tokens[2] === 'going!' ? guests.push(tokens[0]) : console.log(`${tokens[0]} is not in the list!`);
        }
      }
    
      for (let guest of guests) {
        console.log(guest);
      }
    }
    