PEP-3107 introduced the concept of annotations. The basic idea of them is to hint to the readers of the code about what to expect as values of arguments in functions. The use of the word hint is not casual; annotations enable type hinting, which we will discuss later on in this chapter, after the first introduction to annotations.
Annotations let you specify the expected type of some variables that have been defined. It is actually not only about the types, but any kind of metadata that can help you get a better idea of what that variable actually represents.
Consider the following example:
class Point: def __init__(self, lat, long): self.lat = lat self.long = long def locate(latitude: float, longitude: float) -> Point: """Find ...
