How can I make a program that add and edit but cant add or edit if its already in the list

Question

Ex:
import module_MFM_operation
C=0
while c != 'Y':
print("Food Menu")
print("[A] add food")
print("[E] edit food")
c=input("Enter your Choice:")
c = module_MFM_operation.ope(c)
import myra_add,myra_edit
foodlist=[]
def ope(ch):
if ch == 'A':
c = myra_add.add_1(foodlist)
fruitlist.append(c)
elif ch == 'E':
myra_edit.edit_2(foodlist)
else:
print("\nInvalid Input\n")

But this time using color

Answer 1

#Something like this

num_list=[0,1,2,3,4,5]
for each in range(0,10):
if each not in num_list:
num_list.append(each)
else:
pass
print(num_list)

#also, I am not Filipino, sorry

Answer 2

So you want to use a Hashset?