Name for Python's list index system

[Eddie and Babs]

A much-appreciated feature of Python is its subscripting/indexing system 
which allows you to write

    list[-1]    # Get last element
    list[-2]    # Get 2nd to last element

...etc.

Do this feature have any "official" name in Python? If not, then I think it
should. Perhaps "modulo" or "modular" indices? (Could be abbreviated to
"mod")


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