docs: def default_qai(qareport):
      """QAI = 2 * (TP * (PT/PNC) * COV) / (1 + exp(MSE/tau))
  
      Where:
          TP: If all tests passes is 1, 0 otherwise.
          PT: Processors and commands tested.
          PCN: The number number of processors (Loader, Steps and Alerts)
               and commands.
          COV: The code coverage (between 0 and 1).
          MSE: The Maintainability and Style Errors.
          tau: Tolerance of style errors per file
  
      """
      TP = 1. if qareport.is_test_sucess else 0.
      PCN = qareport.processors_number + qareport.commands_number
      PT_div_PCN = float(qareport.pc_tested_number) / PCN
      COV = qareport.coverage_line_rate
      tau = get_tau()
  
      total_tau = float(tau) * len(qareport.project_modules)
      style = 1 + math.exp(qareport.style_errors / total_tau)
  
      result = (2 * TP * PT_div_PCN * COV) / style
      return result