anchor.diff:          double base);
   ----
   Compute the point-wise mutual information of an combination of events
  +
  +[horizontal]
  +Header::
  +    `inform/shannon.h`
   ****
   
   ****
  
positive.code:         size_t event_marginal, double base);
  ----
  Compute the point-wise conditional entropy of a combination of events
  ****
  
  ****
  
negative.code: 
  This function will return `NaN` if `inform_shannon` returns `NaN` when applied to any of the
  distribution arguments.
  
  [horizontal]
  Header::
      `inform/shannon.h`
  ****
  
  ****
  