function in python for uppercase or lowercase an entire string code example

Example 1: converting capital letters to lowercase and viceversa in python

s=input()
new_str=""
for i in range (len(s)):
    if s[i].isupper():
        new_str+=s[i].lower()
    elif s[i].islower():
        new_str+=s[i].upper()
    else:
        new_str+=s[i]
print(new_str)

Example 2: python method to check for uppercase character

a="DEMO"
print(a.isupper())