code: public static <C extends Sequence<D>, D extends Compound> DistanceMatrix poissonDistance(
  			MultipleSequenceAlignment<C, D> msa) throws IOException {
  
  		Msa fMsa = ForesterWrapper.convert(msa);
  		DistanceMatrix DM = PairwiseDistanceCalculator
  				.calcPoissonDistances(fMsa);
  
  		return DM;
  	}
docs: The Poisson (correction) evolutionary distance (d) is a function of the
  fractional dissimilarity (D), given by:
  
  <pre>
  d = -log(1 - D)
  </pre>
  
  The gapped positons in the alignment are ignored in the calculation. This
  method is a wrapper to the forester implementation of the calculation:
  {@link PairwiseDistanceCalculator#calcPoissonDistances(Msa)}
  
  @param msa
  MultipleSequenceAlignment
  @return DistanceMatrix
  @throws IOException