@@ -0,0 +1,247 @@
+package net.zero918nobita.smilepp.frontend;%0A%0Apublic class Builder %7B%0A  private String source;%0A%0A  public Builder() %7B%0A    source = %22%22;%0A  %7D%0A%0A  public String toString() %7B%0A    return source;%0A  %7D%0A%0A  public void addStm(Stm stm) %7B%0A    source += stm;%0A  %7D%0A%7D%0A

Add `Builder` class