code: private void updateAromaticTypesInFiveMemberRing(int[] cycle, String[] symbs) {
  
          final String hetro = symbs[cycle[0]];
  
          // simple conditions tell is the 'IM' and 'AN' flags
          final boolean imidazolium = NCN_PLUS.equals(hetro) || NGD_PLUS.equals(hetro);
          final boolean anion = "NM".equals(hetro);
  
          symbs[cycle[0]] = hetroTypes.get(hetro);
  
          symbs[cycle[1]] = getAlphaAromaticType(symbs[cycle[1]], imidazolium, anion);
          symbs[cycle[4]] = getAlphaAromaticType(symbs[cycle[4]], imidazolium, anion);
          symbs[cycle[2]] = getBetaAromaticType(symbs[cycle[2]], imidazolium, anion);
          symbs[cycle[3]] = getBetaAromaticType(symbs[cycle[3]], imidazolium, anion);
  
      }
docs: Update the symbolic for a 5-member cycle/ring. The cycle should first be normalised with
  {@link #normaliseCycle(int[], int[])} to put the unique 'pi-lone-pair' in position 1 (index
  0). Using predefined mappings the symbolic atom types are updated in the 'symbs[]' vector.
  
  @param cycle normalised 5-member cycle (6 indices)
  @param symbs vector of symbolic types for the whole structure