For Python, a tuple is a data type or object. A tuple could contain multiple data types such as integer, float, string, and even another tuple. All data items are included in a pair of parentheses as shown in the following example:

>>>x=('John',21)
>>>x
('John', 21)

We can use the len() function to find out how many data items are included in each variable. Like C++, the subscript of a tuple starts from 0. If a tuple contains 10 data items, its subscript will start from 0 and end at 9:

>>>x=('John',21)
>>>len(x)
2
>>>x[0]
'John'
>>>type(x[1])
<class 'int'>

The following commands generate an empty tuple and one data item separately:

>>>z=()
>>>type(z)
<class 'tuple'>
>>>y=(1,)          # generate one item tuple
>>>type(y)
<class 'tuple'>
>>>x=(1)         # is x a tuple?

For a tuple, one of its most important features as shown in the following example, is...