code: public static String expand(final char a, final char b) {
  		final StringBuilder out = new StringBuilder();
  
  		if (a < b) {
  			char c = a;
  			while (c <= b) {
  				out.append(c);
  				c = (char) (c + 1);
  			}
  		} else if (a > b) {
  			char c = a;
  			while (c >= b) {
  				out.append(c);
  				c = (char)(c - 1);
  			}
  		}
  
  		return out.toString();
  	}
docs: Expands the characters between {@code a} and {@code b}.
  
  @param a the start character.
  @param b the stop character.
  @return the expanded characters.