Yea, if I always include the structure, we lose other parts of the top level dictionary.
```
Given: 
hash = {'a': {
  'b': 'c',
  'd': 'e',
  }
}

Running an update with the dict {'a': {'b':'f'}} would result in us losing the value of hash['a']['d']

hash= {'a': {
  'b': 'f',
  },
}
```