Len and Sum

Reducing functions

In the earlier chapter on Iterators, we divided the built-in iterator functions into groups:

• Transforming functions
• Reducing functions
• Converting functions
• Primitive functions

In this chapter, we will cover the reducing functions.

A reducing function takes all the values from an iterable and reduces them to a single representative value. For example, sum adds all the values in an iterable and returns the total value.