input: Write a function to filter out all negative numbers from the given matrix. The function should return a new matrix where all negative numbers have been replaced with 0. If the input is an empty matrix, return an empty matrix.
  import numpy as np
  
  def filter_out_negative(matrix):
      if not matrix:
          return []
      matrix = np.array(matrix)
      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]]), np.array([[0, 0], [0, 0]]))
  assert np.array_equal(filter_out_negative([[1, 2], [3, 4]]), np.array([[1, 2], [3, 4]]))
  assert np.array_equal(filter_out_negative([]), [])
output: 
  def filter_out_negative(matrix):
      if not matrix:
          return []
      matrix = np.array(matrix)
      matrix[matrix < 0] = 0
      return matrix
  