input: Write a function to filter out all negative numbers from the given matrix. If the matrix contains any negative numbers, replace them with 0. If the given matrix is empty, return an empty list.
  assert filter_out_negative([[-1, 2, -3], [-4, 5, 6], [-7, 8, 9]]).tolist() == [[0, 2, 0], [0, 5, 6], [0, 8, 9]]
  assert filter_out_negative([]) == []
output: def filter_out_negative(matrix):
      if not matrix:
          return []
      return [[0 if x < 0 else x for x in row] for row in matrix]