The standard Python interpreter uses the GNU Readline library and makes it easy to recall what you've previously typed. The up and down arrow keys allow you to move up and down through your input.

The other is to store values to match as keys in a dictionary, then use the values to take an action—e.g., store a function as a value and use the key or some other variable as input.

For some time now, Python developers have been able to “annotate” names with type information. With Python 3.5, type hints officially became part of the language (see PEP 484).