text: # Guess -> implement binary search -> O(log n)
  # update: Guess was right!
  # will implement for the exercise
  
  def checkInList(numberList, num):
      # these need to be outside indexes
      firstIx = -1
      lastIx = len(numberList)
  
  
      while firstIx+1 < lastIx:
          midDist = (lastIx - firstIx) // 2
          midIx = firstIx + midDist
  
          if num == numberList[midIx]:
              return True
          elif num < numberList[midIx]:
              lastIx = midIx
          elif num > numberList:
              firstIx = midIx
  
      return False
  