ltable implementation

["CHU Run-min" <churunmin@...>]

typedef union TKey {
  struct {
    TValuefields;
    struct Node *next;  /* for chaining */
  } nk;
  TValue tvk;
} TKey;


typedef struct Node {
  TValue i_val;
  TKey i_key;
} Node;


Why TKey has a member 'tvk'?
In ltable.c, I found two macros: gval and key2tval.
Why there is one key but two values?