How to use a variable across multiple functions

I am trying to use two variables (i, and q) across three functions. I want to test whether i and q are valid after each input . If they are then they will be added to list and the while loop continues. If they are not valid Then the function will stop and all input will be taken and presented. I have tried to make both i and q global variables but it does not seem to work as it is saying that "i" is not defined. How do I check the i and q variables in separate functions?

Any help would be really appreciated as I am only new and thought this should work.

I didn’t know what to add so I have put down the three functions in full below:

def add_item():
    code_inputed = []
    quan_inputed = []
    while True:
        i = input("enter code: ")
        return i 
        if i != "END":
            q = input("enter quantity: ")
            return q
            VC()
            VQ()
            if VC == True and VQ == True:
                code_inputed.append(int(i))
                quan_inputed.append(int(q))
            elif VC == True and VQ == False:
                print("Invalid Quanity")
                break
            elif VC == False and VQ == True:
                print ("Invalid code")
                break 
            else:
                print("Invalid inputs")
                break 
    return code_inputed,quan_inputed
        
def VC():
    global i 
    minimum = 0
    maxiumum = 39 
    if i == "END":
        return False
    elif int(i) > minimum and int(i) <= maximum:
        return True
    else:
        return False
   
    
def VQ():
    global q
    minimum = 0
    maxiumum = 49
    if int(q) > minimum and int(q):
        return True
    else:
        return False

Thank you for any help

>Solution :

Looks like you need some help here. First of all the global keyword is for functions where you are setting the global variable. Also, forget about globals. Pass i and q to the functions directly. Then set those calls equal to variables and check those variables.

vc_result = VC(i)
vq_result = VQ(q)

if vc_result == True and vq_result == True:
  ...

Plus, return immediately exits the function so no processing will continue. Those should be removed. I recommend reviewing tutorials on python functions to fill in your knowledge.