Switch statement

balancing_brackets

if string[i] == '}' || ')' || ']'
  case string[i]
  when "]"
      if s.topFront == "["
          s.popFront
      else
          return false
      end
  when ")"
      if s.topFront == "("
          s.popFront
      else
          return false
      end
  when "}"
      if s.topFront == "{"
          s.popFront
      else
          return false
      end
  end
end