code: public static ImmutableSet<String> lowercaseWordSet(final Class<?> origin, final String resource,
                                                          final boolean eliminatePrepAndConj) throws IOException {
          return ImmutableSet.copyOf(new HashSet<String>() {{
              readResource(origin, resource, new NullReturnLineProcessor() {
                  @Override
                  public boolean processLine(@Nonnull final String line) {
                      final String l = simplify(line);
                      if (!l.isEmpty() && !l.startsWith("#")) {
                          for (final String part : SPACES.split(l)) {
                              if (eliminatePrepAndConj) {
                                  final String wordType = Dictionary.checkup(part);
                                  if (wordType != null && (wordType.startsWith("IN") || wordType.startsWith("CC"))) {
                                      continue;
                                  }
                              }
                              // add to the containing HashSet we are currently in the init block of
                              add(toEngLowerCase(clean(part)));
                          }
                      }
                      return true;
                  }
              });
          }});
      }
docs: Returns a Set containing only single words.