code: def S_white(x, d):
      """simple white heteroscedasticity robust covariance
      note: calculating this way is very inefficient, just for cross-checking
      """
      r = np.ones(d.shape[1])  # only points on diagonal
      return aggregate_cov(x, d, r=r, weights=None)
  
file_path: statsmodels/statsmodels/sandbox/panel/sandwich_covariance_generic.py
imports: import numpy
label_desc: Use image node_id 7 for calling a global function with example usage: S_white(x, d) and returns: aggregate_cov