Append lists of a dictionary

I have a dictionary with values are lists.

n = {'d1': [1, 2, 3], 'd2': ['a', 'b', 'c']}
m = {'d1': [4, 5], 'd2': ['d', 'e']}

I am trying to have as an output.

{'d1': [1, 2, 3, 4, 5], 'd2': ['a', 'b', 'c', 'd', 'e']}

I tried the following:

for k in n:
    for k in m:
        n[k] += m[k]

The above code gives a wrong output.

> print(n)
> {'d1': [1, 2, 3, 4, 5, 4, 5], 'd2': ['a', 'b', 'c', 'd', 'e', 'd', 'e']}

>Solution :

• You can’t use k twice, the inner one overrides the outer one.
• You never check if you are adding the same keys.

Assuming n is the "master" dictionary, you don’t even need the inner loop:

for k in n:
    n[k] += m[k]

will result with n being

{'d1': [1, 2, 3, 4, 5], 'd2': ['a', 'b', 'c', 'd', 'e']}