code: public static double getComposition(ProteinSequence sequence, ATTRIBUTE attribute, GROUPING group) throws Exception{
  		return new ProfeatPropertiesImpl().getComposition(sequence, attribute, group);
  	}
docs: An adaptor method which returns the composition of the specific grouping for the given attribute.
  
  @param sequence
  a protein sequence consisting of non-ambiguous characters only
  @param attribute
  one of the seven attributes (Hydrophobicity, Volume, Polarity, Polarizability, Charge, SecondaryStructure or SolventAccessibility)
  @param group
  the grouping to be computed
  @return
  returns the composition of the specific grouping for the given attribute
  @throws Exception
  throws Exception if attribute or group are unknown