typedef struct SingleLinkedStack<Type, Isa> impl Stack {
  struct Element* top;
} SingleLinkedStack;

/*
    // Stack Interface
    struct Stack {
        union Data* stack;
        union Data* data;
        union Data* data1;
        enum Code whenEmpty;
        enum Code clear;
        enum Code push;
        enum Code pop;
        enum Code pop2;
        enum Code isEmpty;
        enum Code get;
        enum Code get2;
        enum Code next;
    } Stack;
    // Stack implementations
    struct SingleLinkedStack {
        struct Element* top;
    } SingleLinkedStack;
    */