gistfile1.txt

  const grades = ['a', 'a', 'b', 'a', 'd', 'a', 'b']
  const uniqueGrades = new Set(grades)
  console.log('uniqueGrades', uniqueGrades)
  const uniqueGradesArray = [...uniqueGrades]
  console.log('uniqueGradesArray', uniqueGradesArray)

  const set = new Set()
  set.add(1)
  set.add('hello')
  set.add(true)
  console.log('initial set', set)

  set.add(1)
  set.add(1)
  set.add(1)
  set.add(2)
  set.delete('hello')

  console.log('final set', set)
  const hasOne = set.has(1)
  const hasFive = set.has(5)
  console.log('hasOne', hasOne)
  console.log('hasFive', hasFive)