#include <stddef.h>
#include <stdbool.h>
#include <data/missing-values.h>
-
-#include <stddef.h>
-#include <data/missing-values.h>
+#include <data/value.h>
typedef const struct variable *variable_pair[2];
const struct variable **vars;
size_t n_vars;
+ union value val1, val2;
const struct variable *indep_var;
};