Save the Grid

A tiny image is stored as a grid of numbers: a list of rows, where each row is a list of whole numbers.

Write save_grid(path, grid). Write the grid into the file called path so that:

• each row goes on its own line,
• the numbers in a row are separated by one space,
• every line ends with \n, including the last.

A row with no numbers becomes an empty line (just \n). An empty grid gives an empty file.

Then read the file back and return the text.