• raise: Raise our own exception

#File Not Found

try:
	file = open("a_file.txt")
	a_dictionary = {"key": "value"}
	print(a_dictionary["key"]

except FileNotFoundError:
	file = open("a_file.txt", "w")
	file.write("Something")

except Keyerror as error_message:
	print(f"That key {error_message} does not exist.")

else:
	content = file.read()
	print(content)

finally:
	raise TypeError("This is an error that I made up.")

Example

height = float(input("Height: "))
weight = int(input("Weight: "))

if height > 3:
	raise ValueError("Human Height should not be over 3 meters.")

bmi = weight / height ** 2
print(bmi)