def is?(state)
      if state.is_a?(Array)
        state.include? current
      else
        state == current
      end
    end
def is?(state)
      if state.is_a?(Array)
        state.include? current
      else
        state == current
      end
    end
Check if current state matches provided state

 @example
   fsm.is?(:green) # => true

 @param [String, Array[String]] state

 @return [Boolean]

 @api public