from itertools import zip_longest
def myfunc(s):
    return ''.join(map(''.join, zip_longest(s[::2].upper(), s[1::2], fillvalue='')))

print(myfunc('Hello World'))

def myfunc(str):
    new_str = ''
    for index,char in enumerate(str):
        if index % 2 == 0:
            new_str += char.upper()
        else:
            new_str += char
    return new_str

print(myfunc('Hello World'))