input: Write a function to filter out all negative numbers from a given matrix and replace them with 0.
  import numpy as np
  
  def filter_out_negative(matrix):
    # Convert matrix to numpy array
    matrix = np.array(matrix)
    # Find all negative numbers and set them to 0
    matrix[matrix < 0] = 0
    return matrix
  
  assert np.array_equal(filter_out_negative([[-1, 2, -3], [-4, 5, 6], [-7, 8, 9]]), np.array([[0, 2, 0], [0, 5, 6], [0, 8, 9]]))
  assert np.array_equal(filter_out_negative([[1, -2, 3], [4, -5, 6], [-7, 8, -9]]), np.array([[1, 0, 3], [4, 0, 6], [0, 8, 0]]))
  assert np.array_equal(filter_out_negative([[1, 2, 3], [4, 5, 6], [7, 8, 9]]), np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]))
  assert np.array_equal(filter_out_negative([]), np.array([]))
output: 
  def filter_out_negative(matrix):
    matrix = np.array(matrix)
    matrix[matrix < 0] = 0
    return matrix
  