Voice TV Control Voice TV Control
RU English

The technologies are rapidly evolving - only 50 years ago a simple black-and-white TV was a luxury! And now even a cool big color TV with remote control is a common thing. Let's try to improve our TV and add the voice control to it! To begin with, we’ll write the simple prototype in Python. It’ll use the following commands:

first_channel() - turns on the first channel from the list.
last_channel() - turns on the last channel from the list.
turn_channel(N) - turns on the N channel. Pay attention that the channel numbers start from 1, not from 0.
next_channel() - turns on the next channel. If the current channel is the last one, turns on the first channel.
previous_channel() - turns on the previous channel. If the current channel is the first one, turns on the last channel.
current_channel() - returns the name of the current channel.
is_exist(N/'name') - gets 1 argument - the number N or the string 'name' and returns "Yes", if the channel N or 'name' exists in the list, or "No" - in the other case.

The default channel turned on before all commands is №1.
Your task is to create the VoiceCommand class and methods described above.
In this mission you could use the Iterator ... design pattern.

You should be an authorized user in order to see the full description and start solving this mission.