def set(key, value)
      @memory[key] = value
      trim(key) if @memory[key].is_a? Array
    end
def set(key, value)
      @memory[key] = value
      trim(key) if @memory[key].is_a? Array
    end
Sets a value to @memory.

 @param [Symbol] key Key to set.

 @return [void]