How to use negate function with balanced ternary numbers?

Question

I've been trying to convert balanced ternary numbers through the negate function in python

def convert_to_balanced_ternary(n):
if n == 0:
    return '0'
negative = n < 0
bt = ''
while n > 0:
    r = n % 3
    if r == 0:
        bt = '0' + bt
        n = n // 3
    elif r == 1:
        if negative:
            bt = '-' + bt
        else:
            bt = '+' + bt
        n = n // 3
    else: 
        if negative:
            bt = '+' + bt
        else:
            bt = '-' + bt
        n = (n + 1) // 3
return bt

def negate(n):
    temp = n.replace('-', '+') or n.replace('+', '-') or n.replace('0', '0')
    return temp

And I can get the '-' to convert to '+' but '+' won't convert to '-'. '0' seems to pass through just fine.

negate('+-0')
'++0'