#	ref: Zybooks Chapter 7.9 Lab: Palindrome

#  simple is_palindrome.
def is_palindrome_1(s):
    pass

#   using an alternative method.
def is_palindrome_2(s):
    pass
    
def is_palindrome_3(s):
    #   case insensitive
    pass
    
def is_palindrome_4(s):
    #   case insensitive and remove non-alphabetic characters.
    pass
    
s1 = "racecar"
s2 = "Racecar"
s3 = "Hello world"
s4 = "A Toyota's a Toyota."
print(f"s1: {s1}")
print(f"s2: {s2}")
print(f"s3: {s3}")
print(f"s4: {s4}")

"""
print(f"is_palindrome_1(s1): {is_palindrome_1(s1)}")
print(f"is_palindrome_1(s2): {is_palindrome_1(s2)}")
print(f"is_palindrome_1(s3): {is_palindrome_1(s3)}")
print(f"is_palindrome_1(s4): {is_palindrome_1(s4)}")

print(f"is_palindrome_2(s1): {is_palindrome_2(s1)}")
print(f"is_palindrome_2(s2): {is_palindrome_2(s2)}")
print(f"is_palindrome_2(s3): {is_palindrome_2(s3)}")
print(f"is_palindrome_2(s4): {is_palindrome_2(s4)}")


print(f"is_palindrome_3(s1): {is_palindrome_3(s1)}")
print(f"is_palindrome_3(s2): {is_palindrome_3(s2)}")
print(f"is_palindrome_3(s3): {is_palindrome_3(s3)}")
print(f"is_palindrome_3(s4): {is_palindrome_3(s4)}")    

print(f"is_palindrome_4(s1): {is_palindrome_4(s1)}")
print(f"is_palindrome_4(s2): {is_palindrome_4(s2)}")
print(f"is_palindrome_4(s3): {is_palindrome_4(s3)}")
print(f"is_palindrome_4(s4): {is_palindrome_4(s4)}")   
"""