Appjar label won't update

Question

link to code in pastebin I'm new to Python, and I attempted to create a calculator application. I'm using the Appjar library for my calculator GUI. The calculator works fine, but the appjar label "bar" will not update, despite changes in the variable accumulator. I have attempted to add loops, appjar's .after() function, and messing with appjar's automatic updating system, but I cannot seem to fix the problem.

#define variables
error=''
accumulator = 0
mem = 0
op = ''
 
#import GUI
from appJar import gui
app=gui("Grid Demo", "500x600")
app.setSticky("news")
app.setExpand("both")
app.setFont(20)
 
       
# Do the math will take the accumulator and memory registers and perform the prevailing operation on them.
# It returns the result, as an integer
def doTheMath(a,b,o):
    if o == "add":
        return a + b
    if o == "sub":
        return b - a
    if o == "mul":
        return a * b
    if o == "div":
        return b/a
 
    #press function defines the output of each button.
def press(button):
    global accumulator
    global mem
    global op
 
    print ("A button was pressed: " + button)
    if button == "C":
        accumulator = 0
        op = ""
        mem = 0
    elif button == "=":
        accumulator = doTheMath(accumulator,mem,str(op))
        mem = 0
        op = ""
    elif button == "+":
        op = "add"
        mem = accumulator
        accumulator = 0
    elif button == "-":
        op = "sub"
        mem = accumulator
        accumulator = 0
    elif button == "x":
        op = "mul"
        mem = accumulator
        accumulator = 0
    elif button == "÷":
        op = "div"
        mem = accumulator
        accumulator = 0
    else:
        accumulator = accumulator * 10 + int(button)
    print ("Acc: " + str(accumulator) + ", op: " + op + ", mem: " + str(mem))
    app.go()
   
       
    #define widgets in GUI
app.addLabel("bar", error+str(accumulator), 0, 0, 3)
app.addButtons(["1"], press, 3, 0)
app.addButtons(["2"], press, 3, 1)
app.addButtons(["3"], press, 3, 2)
app.addButtons(["4"], press, 2, 0)
app.addButtons(["5"], press, 2, 1)
app.addButtons(["6"], press, 2, 2)
app.addButtons(["7"], press, 1, 0)
app.addButtons(["8"], press, 1, 1)
app.addButtons(["9"], press, 1, 2)
app.addButtons(["0"], press, 4, 1)
app.addButtons(["+"], press, 3, 3)
app.addButtons(["-"], press, 4, 3)
app.addButtons(["x"], press, 2, 3)
app.addButtons(["÷"], press, 1, 3)
app.addButtons(["="], press, 4, 2)
app.addButtons(["C"], press, 4, 0)
app.go()

Answer 1

Appjar needs .setlable() to be referenced anytime any variable within "bar" changes, I made a function called changeLable(),

def changeLabel():  
    app.setLabel("bar", error+str(accumulator))

That when referenced at the end of the set of if statements, changes the label "bar", to error+str(accumulator.
Credit to jasonharper.