let none_alone = (coll, fit) => {
  let[first,second,third, ...tail] = [...coll]
  let skip_one = () =>  ([first, second, third, ...tail] =
                          [second, third, ...tail])
   let skip_third = () => ([first, second, third, ...tail] =
                           [...tail])
   while(first !== undefined) {
      if(!fit(first)) skip_one()
      else if(!fit(second)) return false
      else if(!fit(third)) skip_third()
      else                 skip_one()
  }
  return true
}

let gHappy = (str) => none_alone(str, (c) => (c == 'g'))