class_docstr: class for the probability distribution of total runs
  
  This is the exact probability distribution for the (Wald-Wolfowitz)
  runs test. The random variable is the total number of runs if the
  sample has (n0, n1) observations of groups 0 and 1.
  
  
  Notes
  -----
  Written as a class so I can store temporary calculations, but I do not
  think it matters much.
  
  Formulas taken from SAS manual for one-sided significance level.
  
  Could be converted to a full univariate distribution, subclassing
  scipy.stats.distributions.
  
  *Status*
  Not verified yet except for mean.
code: def pdf(self, r):
      r = np.asarray(r)
      r_isodd = np.mod(r, 2) > 0
      r_odd = r[r_isodd]
      r_even = r[~r_isodd]
      runs_pdf = np.zeros(r.shape)
      runs_pdf[r_isodd] = self.runs_prob_odd(r_odd)
      runs_pdf[~r_isodd] = self.runs_prob_even(r_even)
      return runs_pdf
  
imports: import numpy
  from scipy import stats
  from scipy.special import comb
  import warnings
  from statsmodels.tools.validation import array_like
label_desc: Use image node_id 4 for calling the TotalRunsProb obj's underlying member method code with example usage: obj.pdf(r) and returns: runs_pdf