how to open a file by passing a variable name which contains the directory where the file is located in python?

Question

I'm working on a function where I need to open a file e.g. "hello.txt" by passing a variable name that contains a directory of where the file is located instead of the file name. Below is a dummy code that I have designed for this. In short I need to be able to open a file which is located in that directory by passing a directory name as you can see in updated.

def folder_things():
path = 'C:\\Users\\blazh\\Documents\\Vladyslav\\City-Project\\Python\\'
folder_code = "518Z%"
updated = path + folder_code
cwd = os.listdir(updated)
print("You have:", cwd)

st = ""
for x in cwd:
    st += x

print(st)

# BECOMES A STRING
str(st)
print(type(st))
print(st)
final = ("'"+st+"'")
f = open(st, "r")
print(f)