char **strv_env_delete(char **x, unsigned n_lists, ...);
char **strv_env_set(char **x, const char *p);
+char **strv_env_unset(char **l, const char *p);
char *strv_env_get_with_length(char **l, const char *name, size_t k);
char *strv_env_get(char **x, const char *n);