code: public static AtomContactSet getAtomsInContact(Chain chain1, Chain chain2,
  			double cutoff, boolean hetAtoms) {
  		return getAtomsInContact(chain1, chain2, null, cutoff, hetAtoms);
  	}
docs: Returns the set of inter-chain contacts between the two given chains for
  all non-H atoms. Uses a geometric hashing algorithm that speeds up the
  calculation without need of full distance matrix. The parsing mode
  {@link FileParsingParameters#setAlignSeqRes(boolean)} needs to be set to
  true for this to work.
  
  @param chain1
  @param chain2
  @param cutoff
  @param hetAtoms
  if true HET atoms are included, if false they are not
  @return