code: def count_het(self, allele=None, axis=None):
          
          b = self.is_het(allele=allele)
          return np.sum(b, axis=axis)
docs: Count heterozygous genotypes.
  
          Parameters
          ----------
          allele : int, optional
              Allele index.
          axis : int, optional
              Axis over which to count, or None to perform overall count.