In the first session we have explored some basic issues about a DNA sequence. The specific DNA sequence 'atcgat' was one of our data. For computer scientists this is also a value. During the program execution values are represented in the memory of the computer. In order to interpret these representations correctly values have a type.

	Type
	Types are sets of data or values sharing some specific properties and their associated operations.

We have modeled the DNA sequence, out of habit, as a string. ^[1] Strings are one of the basic types that Python can handle. In the gc calculation we have seen two other ones: integers and floats. If you are not sure what sort of data you are working with, you can ask Python about it.

>>> type('atcgat')
<type 'str'>
>>> type(1)
<type 'int'>
>>> type('1')
<type 'str'>