new_contents: """
  Statistics.
  """
  
  
  from numpy import exp
  from scipy.stats import rv_continuous
  from scipy.special import gamma
  
  
  class grw_gen(rv_continuous):
      """
      Generalized Reverse Weibull distribution.
  
      PDF:
          
          a/gamma(g) * x^(a*g-1) * exp(-x^a)
  
      for x,a,g >= 0
  
      """
  
      def _pdf(self,x,a,g):
          return a/gamma(g) * pow(x,a*g-1) * exp(-pow(x,a))
  
      def _fitstart(self,data):
          return (2.0,1.0,0.0,0.02)
  
  grw = grw_gen(a=0.0, name='grw', shapes='a,g')
  
subject: Add stats module with GRW distribution.