code: private static char getChar(final String signature, int pos) {
          return pos < signature.length() ? signature.charAt(pos) : (char) 0;
      }
docs: Returns the signature car at the given index.
  
  @param signature
  a signature.
  @param pos
  an index in signature.
  @return the character at the given index, or 0 if there is no such
  character.