Condition check differences and how to organise code?

[adam2020]

ok so I changed the code

def find_filter_output(output,find):
    files = []
    lines = output.split("\n")
    contains = False
    found = False
    findStr = str(find)

    if findStr == "":
        word = "invalid"
        files.append(word)
        return files

here I test to see if findStr is empty by saying if findStr == "", this works great but I noticed when I put a space in between the "" it does not work or become true

so

 if findStr == " "

will give a boolean false value even if findStr is empty, so why does adding a blank space between "" make a difference? I thought that even if I had countless of blank spaces between the "" it would still be an empty string no?