class Solution:
def convertToBase7(self, num: int) -> str:
if num == 0:
return "0"
else:
as_base_7 = ""
is_positive = num >= 0
num = abs(num)
while num > 0:
num, digit = divmod(num, 7)
as_base_7 = str(digit) + as_base_7
return as_base_7 if is_positive else "-" + as_base_7