Sudoku is a logic-based number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row and each 3×3 sub-grid contains all of the digits from 1 to 9. The puzzle creator provides a partially completed grid, which typically has a unique solution.

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For example, the following grid

gives the result:

gives the result:

A puzzle is represented as a list of lists with digits. A zero value means that the value hasn't been set.

**Input: ** The initial 9x9 grid composed by integers as a list of lists.

**Output: ** The result of the sudoku as a list of lists.

**Example:**

checkio([[5, 0, 0, 7, 1,...