remove wrong class_prelude imports

src/flow/traversible/algorithms/contains.rs

@@ -1,4 +1,4 @@
-use crate::{flow::traversible::*, func::class_prelude::MonadFail};
+use crate::{flow::traversible::*, func::fail::*};
 
 pub fn n_contains<'a, T: MonadFail<'a, ()>, A: 'a + Send + Clone, D: 'a + PartialEq>(
     comparator: &'a dyn Comparator<A>,

src/flow/traversible/algorithms/subset.rs

@@ -1,6 +1,6 @@
 use crate::flow::comparator::*;
 use crate::flow::traversible::*;
-use crate::func::class_prelude::MonadFail;
+use crate::func::fail::*;
 
 fn and(_l: (), _r: ()) {}