code: public static int getSymmetryOrder(Map<Integer, Integer> alignment,
  									   final int maxSymmetry, final float minimumMetricChange) {
  		return getSymmetryOrder(alignment, new IdentityMap<Integer>(), maxSymmetry, minimumMetricChange);
  	}
docs: Helper for {@link #getSymmetryOrder(Map, Map, int, float)} with a true
  identity function (X->X).
  
  <p>This method should only be used in cases where the two proteins
  aligned have identical numbering, as for self-alignments. See
  {@link #getSymmetryOrder(AFPChain, int, float)} for a way to guess
  the sequential correspondence between two proteins.
  
  @param alignment
  @param maxSymmetry
  @param minimumMetricChange
  @return