code: def cov_hc1(results):
      """
      See statsmodels.RegressionResults
      """
  
      het_scale = (
          results.nobs / (results.df_resid) * (results.resid**2)
      )
      cov_hc1 = _HCCM(results, het_scale)
      return cov_hc1
  
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 3 for calling a global function with example usage: cov_hc1(results) and returns: cov_hc1