General¶

Python is a dynamic scripting language
Python allows for object oriented programming (OOP) but also for functional programming
- It is possible to define classes with methods
- Instances of classes are called objects
Python uses duck typing
- “If it walks like a duck, and it quacks like a duck, then it must be a duck.”
- It’s based on so called Protocols
- Protocols define the availability of specific methods and their signatures
- Methods of Protocols are (mostly) dunder methods
  - dunder -> double underscore
  - __foo__(...)
  - Most famous the constructor method def __init__(self)
Functions (and therefore also methods) return None implicitly if no return statement is defined or if it has no value.
```
def foo():
  print("foo")
```
is the same as
```
def foo():
  print("foo")
  return
```
is the same as
```
def foo():
  print("foo")
  return None
```