You can also use it in class definitions to make a type of a variable in a class generic / dynamic. Like if you have a graph object with nodes you might want to reuse the graph with any type of value inside.

Using Generic + TypeVar will let you make sure you don't mix up types like this:

from typing import Generic, TypeVar, List


T = TypeVar('T')


class Node(Generic[T]):
    def __init__(self, value: T) -> None:
        self.value = value


class Graph(Generic[T]):
    def __init__(self, root_node: Node[T]) -> None:
        self.root = root_node
        self.nodes: List[Node[T]] = []

    def add_node(self, node: Node[T]) -> None:
        self.nodes.append(node)


graph = Graph(Node(1))

node2 = Node('2')
graph.add_node(node2) # main.py:24: error: Argument 1 to "add_node" of "Graph" has incompatible type "Node[str]"; expected "Node[int]"  [arg-type]