code: def cov_hc0(results):
      """
      See statsmodels.RegressionResults
      """
  
      het_scale = results.resid**2  # or whitened residuals? only OLS?
      cov_hc0 = _HCCM(results, het_scale)
  
      return cov_hc0
  
imports: import numpy
  from statsmodels.tools.grouputils import combine_indices, group_sums
  from statsmodels.stats.moment_helpers import se_cov
label_desc: Use image node_id 2 for calling a global function with example usage: cov_hc0(results) and returns: cov_hc0