(Solved) : Change Postfix Function Prefix Infix Functions Respectively Python Please Possible Add Com Q32005878 . . . .

change the postfix function to a prefix and infix functionsrespectively. In python please.. If possible add comments as itwill be helpful explaining

# Stack.py
class Stack:

#————————————————————

def __init__(self,c):

”’post: creates an empty LIFO stack”’

self.items = []
self.c=c

#————————————————————

def push(self, item):
  
”’post: places x on top of the stack”’

self.items.append(item)

#————————————————————

def pop(self):

”’post: removes and returns the top element of
the stack”’

return self.items.pop()

#————————————————————

def top(self):

”’post: returns the top element of the stack without
removing it”’

return self.items[-1]

#————————————————————

def size(self):

”’post: returns the number of elements in the stack”’

return len(self.items)

def postfix(self, sia):
for i in sia:
if i.isdigit():
self.push(i)
else:
val1 = self.pop()
val2 = self.pop()
self.push(str(eval(val2 + i + val1)))
return int(self.pop())

doc=”231*9-“
nurse = Stack(len(doc))
print(“Value of %s is %d” % (doc, nurse.postfix(doc)))

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