Simple Python Calculator using a Dictionary and Functions for Operators

This lesson creates a simple calculator using a dictionary to look up functions for operators. The point is to practice more with dictionaries, and to learn about higher-order functions.
Source code

Using a Python Dictionary to Give Custom Greetings

This walkthrough of greet-dict.py teaches how to use a dictionary to store customized greetings, how to convert a string to lower case to make lookups easier, and how to see if a key is in the dictionary using in.