Updating nested dict

# https://stackoverflow.com/questions/53429414/how-to-merge-json-files

import json

dict_1 = {
    "level1": {
        "level2": {
            "level3": 0
        }
    }
}

dict_2 = {
    "level1": {
        "level20": {
            "level3": {
                "level4" : 5
            }
        },
        "level2a": {
            "level3": 13
        },
        "level2b": {
            "level3": 42
        }
    }
}

dict_1["level1"].update(dict_2["level1"])

# Pretty-print the result.
print("dict_1 =", json.dumps(dict_1, indent=4))


################
'''
Output:

  dict_1 = {
      "level1": {
          "level2": {
              "level3": 0
          },
          "level20": {
              "level3": {
                  "level4": 5
              }
          },
          "level2a": {
              "level3": 13
          },
          "level2b": {
              "level3": 42
          }
      }
  }

'''