To install typing module, paste the following command into your terminal.

```
pip install typing
```

Then, to import the module into your code, be sure to have the following code at the top of your file:

```python
import typing
```

Installing and Importing Typing

```python
from typing import Optional, List, Tuple

def function(param1: Optional[int], param2: List[int]):
     print(param1, param2)

>>> function(None, [12, 45, 1])
#None [12, 45, 1]
# For this example, param1 had an input of None, while 
# param2 had a parameter of type List inputted. 
# The function's output reflects this.

>>> function(12, [1, 2])
#12 [1,2]
# For this example, param1 had an input of type int, while 
# param2 had a parameter of type List inputted. 
# The function's output reflects this.
```
Type annotations made for each parameter will return a TypeError if the parameter is not of the correct type.


Typing Example

Typing is a module that defines a standard notation for Python function and variable type annotations. The notations can be used to make code more readable, as well as documenting code in a standard format.

California Polytechnic State University, San Luis Obispo

In Python, function parameters refer to the variables that are listed within a function definition. For example, in the function rotate(x, y), the parameters are x and y.

Function Parameters in Python

Functions in Python can have optional parameters. Functions with optional parameters can be called with or without passing an argument through the optional parameters. If no argument is provided, the default value will be passed through the parameter. The default value must be defined with an = sign in the function header. For example, in the function rotate(x, y = 3), y is an optional parameter with a default value of 3.

Learn Before

Related

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