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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def apply_mask(matrix, mask_pattern, matrix_size, is_encoding_region):
 """\ Applies the provided mask pattern on the `matrix`. ISO/IEC 18004:2015(E) -- 7.8.2 Data mask patterns (page 50) :param tuple matrix: A tuple of bytearrays :param mask_pattern: A mask pattern (a function) :param int matrix_size: width or height of the matrix :param is_encoding_region: A function which returns ``True`` iff the row index / col index belongs to the data region. """

    for i in range(matrix_size):
        for j in range(matrix_size):
            if is_encoding_region(i, j):
                matrix[i][j] ^= mask_pattern(i, j)