how to use a def function in python code example

Example 1: python function

def name():#name of the def(function);
  print("Hallo, World!")#Output is Hallo, World!;
  
name()#Name of the def, the programm will jump to the def;

#output:
#Hallo, World!

Example 2: python functions

# Python Functions
def a_function(): #def FUNCTIONNAMEHERE(): Function content
  print("Hello World!")
  return 0
def answerValid(prompt, correct_answers, invalid): # Functions can also have parameters, or variables that can be used only in tha function
  while True:
    user = input(prompt)
    if user in correct_answers:
      break 
      return user # Example Function
   	else:
      print(invalid)

a_function() # To call a function; Prints 'Hello World!'
# But if this is done:
function_called = a_function() # function_called would contain a 0, because the function returns 0
answer = answerValid("What is 8 * 8?", [64], "Invalid Option")
print(answer) # Prints 64, because that is the only possible answer