What is wrong with thiis code. I am trying to write a program of infix to postfix conversion in python - stack

Question

infix to postfix conversion using python
I am using deque for creating stack
from collections import deque
class Infix_to_prefix:
def __init__(self):
self.container = deque()
self.output = deque()
def push(self,val):
self.container.append(val)
def pop(self):
self.container.pop()
def peek(self):
return self.container[-1]
def is_empty(self):
if len(self.container)==0:
return True
else:
return False
def is_operator(self, ch):
if ch in "+-*/^":
return True
else:
return False
def is_operand(self,ch):
if (ch>='A' and ch<='Z') or (ch>='a' and ch<='z'):
return True
else:
False
def ranking(self, top, ch):
rank = {
'+': 1,
'-': 1,
'*': 2,
'/': 2,
'^': 3
}
if rank[top]<rank[ch]:
return True
else:
return False
def Conversion(self, exp):
for ch in exp:
if self.is_operand(ch):
self.output.append(ch)
elif self.is_operator(ch):
while True:
if self.is_empty():
self.push(ch)
else:
top = self.peek()
if top == '(':
self.push(ch)
break
elif self.ranking(top, ch):
self.push(ch)
break
else:
cpop = self.pop()
self.output.append(cpop)
elif ch == '(':
self.push(ch)
elif ch == ')':
cpop = self.pop()
while cpop!='(':
self.output.append(cpop)
cpop = self.pop()
while not self.is_empty():
cpop = self.pop()
self.output.append(cpop)
print(("").join(self.output))
exp = "a+b*(c^d-e)^(f+g*h)-i"
s = Infix_to_prefix()
s.Conversion(exp)
When I am running this code it just keep running.
Is there is another method or another program for solving infix to postfix.
point out what is wrong in this code.
Please ignore from this line
also tell me why stack flow always keeps telling me to add some more detail every time i atry to ask a question.