Sum indices
Level: Intermediate (score: 3)
Write a function that accepts a list of strings and returns the total of the indices of the items.
Example 1: ['a', 'b', 'c'] => 0 + 1 + 2 = 3
The indices for duplicate items should be accumulated in the total as they appear.
Example 2: ['a', 'b', 'b', 'c'] => 0 + 1 + (1+2) + 3 = 7
Example 3: ['a', 'b', 'b', 'c', 'a', 'b', 'a'] => 0 + 1 + (1+2) + 3 + (0+4) + (1+2+5) + (0+4+6) = 29