Deep Merge: transliterated from https://gist.github.com/dpatti/178bd9948518256396ff

deep-merge.py

# Deep merge
# 
# - Write a function that takes two dictionaries and returns a new dictionary
#   containing the keys and values from both dictionaries.
# - Neither input should be modified.
# - If the key exists in both dictionaries...
#   ...merge the values if they are both dictionaries.
#   ...give the values in the second dictionary (b) precedence otherwise.

def merge(a, b):
    return  # replace with your solution

# Input for tests
a = {
  "hello": "who?",
  "foo": {
    "bar": 1,
  },
  "first": True,
}

b = {
  "hello": "world!",
  "foo": {
    "baz": 2,
  },
  "second": False,
}

# Test that the merge gives us the expected results
assert merge(a, b) == {
  "hello": "world!",
  "foo": {
    "bar": 1,
    "baz": 2,
  },
  "first": True,
  "second": False,
}

# Test that we have not modified the input
assert a == {
  "hello": "who?",
  "foo": {
    "bar": 1,
  },
  "first": True,
}

assert b == {
  "hello": "world!",
  "foo": {
    "baz": 2,
  },
  "second": False,
}

print("All tests pass!")