if (st.nextToken() != st.TT_EOF) throw new IOException("Extra input: '"+st.ttype+"'");
if (st.nextToken() != StreamTokenizer.TT_EOF) throw new IOException("Extra input: '"+st.ttype+"'");
  private String evalLet(StreamTokenizer st) throws IOException {     String val = evalStrExpr(st);     if (st.nextToken() != st.TT_EOF) throw new IOException("Extra input: '"+st.ttype+"'");     return val;  }