input: from typing import List
  
  def filter_out_negative(matrix: List[List[int]]) -> List[List[int]]:
      """Filters out all negative numbers from the given matrix and replaces them with 0s.
      >>> filter_out_negative([[-1, 2, -3], [-4, 5, 6], [-7, 8, 9]])
      [[0, 2, 0], [0, 5, 6], [0, 8, 9]]
      """
output:     for i in range(len(matrix)):
          for j in range(len(matrix[i])):
              if matrix[i][j] < 0:
                  matrix[i][j] = 0
      return matrix