where should assert be used in python code example

Example 1: python assert

"""Quick note!
This code snippet has been copied by Pseudo Balls.
This is the original answer.
Please consider justice by ignoring his answer.
"""
"""assert:
evaluates an expression and raises AssertionError
if expression returns False
"""
assert 1 == 1  # does not raise an error
assert False  # raises AssertionError
# gives an error with a message as provided in the second argument
assert 1 + 1 == 3, "1 + 1 does not equal 3"
"""When line 7 is run:
AssertionError: 1 + 1 does not equal 3
"""

Example 2: python assert

def input_age(age):
   try:
       assert int(age) > 18
   except ValueError:
       return 'ValueError: Cannot convert into int'
   else:
       return 'Age is saved successfully'
 
print(input_age('23'))  	# This will print
print(input_age(25))  		# This will print
print(input_age('nothing')) # This will raise ValueError which is handled
print(input_age('18'))  	# This will raise AssertionError, program collapses
print(input_age(43))  		# This won't print