Problem:

Model addition on an abacus.

Given two integers of one or more digits, return their sum.

The integers are represented as lists, each containing only one-character strings, such that each one-character string represents a single digit. The sum is similarly a list of one-character strings of single digits.

There is a Pytest test program included in the repository.

The program abacus.py is a solution, as is brute_force_abacus.py. The program abacus_original.py is a shell, to be used in solving the problem.

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