code: def _get_fault_mechanism_flags(self, rake):
          
  
          CN, CR = 0, 0
  
          # Pure Normal: rake = -90
          if rake > -147 and rake < -33:
              CN = -1
  
          # Pure Reverse: rake = 90
          if rake > 67 and rake < 123:
              CR = 1
  
          # Pure Oblique Reverse: rake = 45
          if rake > 33 and rake < 66:
              CR = 0.5
  
          return CN, CR
docs: Return the fault mechanism flag CN and CR, page 23
          CN = -1 for normal (-146<rake<-33), 0 otherwise
          CR = 0.5 for reverse-oblique (33<rake<66), 1 for reverse (67<rake<123)
          and 0 otherwise