U1db implementation

I think maybe I was not clear enough.

What i suggested is to use variables instead of directly using strings when accessing dictionaries. I.e. instead of writing:

    mydict["index"] = value

We would write:

    INDEX_KEY = "index"
    mydict[INDEX_KEY] = value

Then we would have the `INDEX_KEY` variable definition somewhere all parts of the code that need to access those kinds of keys in a dictionary could import from. This is interesting to avoid typos like `mydict["indx"]`, as python would not complain about on compile time, but would complain about `mydixt[INDX_KEY]` if you ever come to write it. Those kinds of bugs are somewhat easy to produce and hard to find, thus the standardization proposed.

Makes sense?