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I have the following error when running printDicts() in my code:

Traceback (most recent call last):
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 238, in <module>
    main()
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 232, in main
    choisesDict[choise]()
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 206, in printDicts
    d = add3dicts(d1,d2,d3)
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 198, in add3dicts
    addD3(list(d3.keys()))
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 194, in addD3
    return addD2(lis[1:])
  File "Desktop\PythonApplication1\PythonApplication1\exercise3.py", line 184, in addD2
    returnDic[lis[0]] = insert2(d2[lis[0]],d3[lis[0]])
KeyError: 8
The code is:
def add3dicts(d1,d2,d3):
    insert3 = lambda x,y,z:tuple(set({x,y,z}))
    insert2 = lambda x,y: tuple(set({x,y}))
    returnDic = dict()
    def addD1(lis):
        if lis == []:
            return
        if(lis[0] in d2 and lis[0] in d3):
            returnDic[lis[0]] = insert3(d1[lis[0]],d2[lis[0]],d3[lis[0]])
            d2.pop(lis[0])
            d3.pop(lis[0])
        elif(lis[0] in d2):
            returnDic[lis[0]] = insert2(d1[lis[0]],d2[lis[0]])
            d2.pop(lis[0])
        elif(lis[0] in d3):
            returnDic[lis[0]] = insert2(d1[lis[0]],d3,[lis[0]])
            d3.pop(lis[0])
        else:
            returnDic[lis[0]] = d1[lis[0]]
        return addD1(lis[1:])
    def addD2(lis):
        if lis == []:
            return
        if(lis[0] in d3):
            returnDic[lis[0]] = insert2(d2[lis[0]],d3[lis[0]])
            d3.pop(lis[0])
        else:
            returnDic[lis[0]] = d2[lis[0]]
        return addD2(lis[1:])
    def addD3(lis):
        if lis == []:
            return
        returnDic[lis[0]] = d3[lis[0]]
        return addD2(lis[1:])
    addD1(list(d1.keys()))
    addD2(list(d2.keys()))
    addD3(list(d3.keys()))
    return returnDic
def printDicts():
    d1 = eval(input("Please enter the first dictionary:"))
    d2 = eval(input("Please enter the second dictionary:"))
    d3 = eval(input("Please enter the third dictionary:"))
    print("The merged dictionary is:")
    d = add3dicts(d1,d2,d3)
    print(d)
    return
I tried everything I knew, searched the Internet and everything, and could not figure out what the error was and how to solve it.
Is the "key" in the error related to the dictionary? If so, then what's the error? The dictionary seems to be well built. If it's not related to the dictionary, then what's the error?
(Sorry if there are errors in English, this is not my native language ..)
                You're trying to get a key 8 from dictionary, which does not exist. 8 is what your list has. Verify which keys are there by outputing returnDic.keys()
– dmitryro
                Jun 26, 2018 at 11:33
                Just a side-recommendation: use pep-8 and good names for your variables and functions to get cleaner code. That will be very helpful not only for others (e.g. on SO), also for you if you look at the code some days later.
– colidyre
                Jun 26, 2018 at 11:43
Obviously, lis[0] contains the value 8 at runtime. Then you try fetch the element with the key 8 in d2 and d3. Either of these dictionaries doesn't contain an element with the given key. That's why the error is raised.
Your code only checks whether lis[0] is in d3, but not d2. So d2 must be the culprit. Try changing your code to:
def addD2(lis):
    if lis == []:
        return
    if(lis[0] in d3 and lis[0] in d2):
        returnDic[lis[0]] = insert2(d2[lis[0]],d3[lis[0]])
        d3.pop(lis[0])
    elif lis[0] in d2:
        returnDic[lis[0]] = d2[lis[0]]
Note: Since I'm not sure what the intended logic of the whole algorithm is, it might not give you the result you expect. But it should avoid the exception.
        
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