contacts = {
  "tom": "122-444-333",
  "jim": "412-1231-121",
  "ron": "8912-121-1212",
  "jake": "333-1881-121"
}

contacts['jane'] = '443-123-991'  # adding new element

contacts['jane'] = '443-123-000'  # update Jane's number

print(contacts['jane'])