code: def mean_center(matrix):
      """Performs mean centering across axis 0
  
      Args:
          matrix (np.ndarray): Input matrix that needs to be mean centered
      """
      avg = np.mean(matrix, axis=0)
      matrix -= avg
  
imports: import numpy
  from sklearn.decomposition import PCA
label_desc: Use image node_id 2 for calling a global function with example usage: mean_center(matrix) without return types