Python Language The Interpreter (Command Line Console) Referring to the last expression


Example

To get the value of the last result from your last expression in the console, use an underscore _.

>>> 2 + 2
4
>>> _
4
>>> _ + 6
10

This magic underscore value is only updated when using a python expression that results in a value. Defining functions or for loops does not change the value. If the expression raises an exception there will be no changes to _.

>>> "Hello, {0}".format("World")
'Hello, World'
>>> _
'Hello, World'
>>> def wontchangethings():
...     pass
>>> _
'Hello, World'
>>> 27 / 0
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: division by zero
>>> _
'Hello, World'

Remember, this magic variable is only available in the interactive python interpreter. Running scripts will not do this.