Defined function is miscounting number of upper/lowercase characters

def letcheck(a):
    upper = 0
    lower = 0
    for letter in a:
        if a.islower():
            lower += 1
        else:
            upper += 1
    print('The number of lowercase letters is', lower)
    print('The number of uppercase letters is', upper)
    return

letcheck('My name is Slugcat')

Hi there. I imagine this is very basic for most of you so forgive me but I can’t figure out why my function is outputting this.

The number of lowercase letters is 0
The number of uppercase letters is 18

Process finished with exit code 0

Why has it counted all characters as uppercase? Please help.
P.S. is there any way to stop it from counting the spaces in the string? Thank you very much.

>Solution :

Change if a.islower() to if letter.islower() as you want to check the case for each letter not a which is the sentence itself. Spaces are counted as uppercase so for an accurate reading loop over the sentence with the whitespace removed.

def letcheck(a):
    upper = 0
    lower = 0
    #Loop over sentence with whitespace removed
    for letter in a.replace(" ",""):
        if letter.islower():
            lower += 1
        else:
            upper += 1
    print('The number of lowercase letters is', lower)
    print('The number of uppercase letters is', upper)
    return

letcheck('My name is Slugcat')