ADT for TV set:
	data:

	members:

It has three basic data items: (1) the on/off setting, (2) the volume setting
(which is int), and (3) the channel setting (which is int.), (4) a 
maximumChannel, and (5) a maximumVolume. A channel setting must be a number from
2 to maximumChannel.  The volume must be a number from 0 to maximumVolume.

It has a secondary data item: mute, which has as its value on/off, (i.e.,
a boolean.).

	methods:

constructor:
INPUT:		int, maximumChannel, int maximumVolume
PRECONDITIONS:  both inputs must be positive.
PROCESS: 	it initializes the TV in the off state, sets channel to 4,
		and sets volume control to maximumVolume/2 (middle range).  The 
		mute is set to the off state.  It assigns the input value of
		maximumChannle to the class member maximumChannel and the same
		for maximumVolume.
		the proper 
OUTPUT:		none
POSTCONDITION:  TV is in off state, channel is 5, volumn is at 7 and mute is
		in the off state.

turnOnSet:
INPUT:		none
PRECONDITIONS:	TV is in off state
PROCESS:	It changes state of TV to on state. 
OUTPUT:		none
POSTCONDITION:  TV is in on state

turnOffSet:
INPUT:		none
PRECONDITIONS:	TV is in on state
PROCESS:	It changes state of TV to off state.
OUTPUT:		none
POSTCONDITION:  TV is in off state

increaseVolume:
INPUT:		none
PRECONDITIONS:	volume must not be at maximumVolume  and the TV is on
PROCESS:	Increases volume by one value.
OUTPUT:		none
POSTCONDITION:  volume has increased by one value.

decreaseVolume
INPUT:		none
PRECONDITIONS:	volume must not be at minimumVolume and the TV is on
PROCESS:	Decreases volume by one value.
OUTPUT:		none
POSTCONDITION:	volume has decreased by one value

changeChannel
INPUT:		integer
PRECONDITIONS:	The TV must be on. The value must be between -1 and
		maximumChannel.
PROCESS:	If integer is > 1, sets channel to value sent it.  If value is
		+1, it increases the current channel value by one (if it is at
		maximumChannle, it goes to 2.  If value is -1, it decreases the 
		value by one (if the current value is 2, it changes to 
		maximumChannel).
OUTPUT:		none
POSTCONDITION:  channel has been changed

getState:
INPUT:		none
PRECONDITIONS:	none
PROCESS:	It returns the current value of state.
OUTPUT:		boolean, which is the state
POSTCONDITION:	none

getMute:
INPUT:		none
PRECONDITIONS:	the TV must be on
PROCESS:	It returns the current value of mute.
OUTPUT:		boolean, which is the mute
POSTCONDITION:	none

getVolume:
INPUT:		none
PRECONDITIONS:	the TV must be on
PROCESS:	It returns the current value of volume.
OUTPUT:		int, which is the volume
POSTCONDITION:	none

getChannel:
INPUT:		none
PRECONDITIONS:	the TV must be on
PROCESS:	It returns the current value of channel.
OUTPUT:		int, which is the channel
POSTCONDITION:	none

changeMute:
INPUT:		none
PRECONDITIONS:	the TV must be on
PROCESS:	It toggles the state of mute.  If on, it becomes off, and
		vice-versa.
OUTPUT:		none 
POSTCONDITION:	mute has changed state