@@ -0,0 +1,354 @@
+package net.zero918nobita.smilepp.frontend;%0A%0Apublic class AssignStm extends Stm %7B%0A  private Variable variable;%0A  private Expression expression;%0A%0A  public AssignStm(Variable variable, Expression expression) %7B%0A    this.variable = variable;%0A    this.expression = expression;%0A  %7D%0A%0A  public String toString() %7B%0A    return variable + %22 = %22 + expression;%0A  %7D%0A%7D%0A

Add `AssignStm` class