diff --git a/README.md b/README.md
index 6aae3c1..b20703e 100644
--- a/README.md
+++ b/README.md
@@ -9,14 +9,14 @@ _So as to avoid re-creating the text in memory, both train and vocab are lazy it
 rltk has the same philosophy: everything is done using iterators (on iterators) on string slices.
 
 Currently in it's infancy (but growing): 
-* rltk::lm::preprocessing::pad_both_ends(\["a","b","c"], 2) -> "\<s>", "a", "b", "c", "\</s>"]
-* rltk::util::pad_sequence == same as above with customisation
-* rltk::util::pad_sequence_left == same
-* rltk::util::pad_sequence_right == same
-* rltk::util::ngrams(\["a","b","c"],2) -> \[\["a", "b"], \["b", "c"]]
-* rltk::util::bigrams(\["a","b","c"]) == ngrams(..., 2) 
-* rltk::util::trigrams(\["a","b","c"]) == ngrams(..., 3)
-* rltk::util::everygrams(\["a","b","c"],2) ==  \[\["a"], \["a", "b"], \["b"], \["b", "c"]]
-* rltk::util::flatten(\[\["a"], \["a", "b"], \["b"], \["b", "c"]]) ==  \[\"a", "a", "b", "b", "b", "c"]
-* rltk::metrics::distance::edit_distance(): calculate the levenshtein distance between two words (see doc)
+* rltk::lm::preprocessing::pad_both_ends
+* rltk::util::pad_sequence
+* rltk::util::pad_sequence_left
+* rltk::util::pad_sequence_right
+* rltk::util::ngrams
+* rltk::util::bigrams 
+* rltk::util::trigrams
+* rltk::util::everygrams
+* rltk::util::flatten
+* rltk::metrics::distance::edit_distance
 
diff --git a/src/lib.rs b/src/lib.rs
index 4cd840c..623b242 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,5 @@
 pub mod lm;
 pub mod util;
-pub mod metrics;
\ No newline at end of file
+pub mod metrics;
+#[cfg(test)]
+pub(crate) mod test;
\ No newline at end of file
diff --git a/src/lm/preprocessing.rs b/src/lm/preprocessing.rs
index 760dd8e..7f5c114 100644
--- a/src/lm/preprocessing.rs
+++ b/src/lm/preprocessing.rs
@@ -2,10 +2,40 @@
 ///
 /// sentence: sequence of words, tokens, to pad, in the form of an Iterator of string slices.
 /// n: the n in n-grams; so for bigrams set to 2, etc
-pub fn pad_both_ends<'a>(text: impl Iterator<Item=&'a str> + 'static, n: usize) -> impl Iterator<Item=&'a str> {
-    crate::util::padding::Padder::new(Box::new(text), true, "<s>", true,"</s>", n)
+pub fn pad_both_ends<'a>(text: impl Iterator<Item=&'a &'a str> + 'a, n: usize) -> impl Iterator<Item=&'a &'a str> {
+    crate::util::padding::Padder::new(Box::new(text), true, &"<s>", true,&"</s>", n)
 }
 
+pub fn padded_everygrams<'a>(sentence: impl Iterator<Item=&'a &'a str> + 'a, n: usize) -> impl Iterator<Item=Box<dyn Iterator<Item=&'a &'a str> + 'a>> + 'a  {
+    crate::util::everygrams(pad_both_ends(sentence, n), n)
+}
 
+#[cfg(test)]
+mod tests{
 
+    use super::*;
 
+    #[test]
+    fn test(){
+        let sentence = vec!["a","b", "c"];
+        let bigrams = padded_everygrams(sentence.iter(),2);
+        for b in bigrams.into_iter(){
+            for o in b{
+                print!("{}, ",o);
+            }
+            println!();
+        }
+        // let bigram1 = vec!["<s>"];
+        // let bigram2 = vec!["<s>", "a"];
+        // let bigram3 = vec!["a"];
+        // let bigram4 = vec!["a", "b"];
+        // let bigram5 = vec!["b"];
+        // let bigram6 = vec!["b", "c"];
+        // let bigram7 = vec!["c"];
+        // let bigram8 = vec!["c", "</s>"];
+        // let bigram9 = vec!["</s>"];
+        // let expected = vec![bigram1.iter(), bigram2.iter(), bigram3.iter(), bigram4.iter(), bigram5.iter(), bigram6.iter(),bigram7.iter(),bigram8.iter(),bigram9.iter()];
+        //
+        // crate::test::should_be_equal_list_of_lists(&mut bigrams, expected)
+    }
+}
\ No newline at end of file
diff --git a/src/test.rs b/src/test.rs
new file mode 100644
index 0000000..6641280
--- /dev/null
+++ b/src/test.rs
@@ -0,0 +1,16 @@
+use std::slice::Iter;
+
+pub fn should_be_equal_lists<'a>(left: impl Iterator<Item=&'a &'a str>, right: Vec<&'a str>) {
+    for (left, right) in left.zip(right.into_iter()) {
+        assert_eq!(*left, right);
+    }
+}
+
+pub fn should_be_equal_list_of_lists<'a>(actual: &mut impl Iterator<Item=impl Iterator<Item=&'a &'a str>>, expected: Vec<Iter<&'a str>>) {
+    for (actual_outer, expected_outer) in actual.zip(expected.into_iter()) {
+        for (actual_inner, expected_inner) in actual_outer.zip(expected_outer) {
+            // println!("{} {}", actual_inner, expected_inner);
+            assert_eq!(actual_inner, expected_inner);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/util/mod.rs b/src/util/mod.rs
index abe0288..c1ceb9d 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -1,6 +1,5 @@
 pub(crate) mod padding;
 pub(crate) mod ngrams;
-
 use padding::Padder;
 
 /// Returns a padded sequence of items before ngram extraction.
@@ -11,7 +10,7 @@ use padding::Padder;
 /// pad_right: if set to true, appends a padding symbol after the sentence
 /// right_pad_symbol: the padding symbol to append
 /// n: the n in n-grams; so for bigrams set to 2, etc
-pub fn pad_sequence<'a>(sentence: impl Iterator<Item=&'a str> + 'static, pad_left: bool, left_pad_symbol: &'static str, pad_right: bool, right_pad_symbol: &'static str, n: usize) -> impl Iterator<Item=&'a str> {
+pub fn pad_sequence<'a>(sentence: impl Iterator<Item=&'a &'a str> + 'a, pad_left: bool, left_pad_symbol: &'a &'a str, pad_right: bool, right_pad_symbol: &'a &'a str, n: usize) -> impl Iterator<Item=&'a &'a str> {
     Padder::new(Box::new(sentence), pad_left, left_pad_symbol, pad_right, right_pad_symbol, n)
 }
 
@@ -19,8 +18,8 @@ pub fn pad_sequence<'a>(sentence: impl Iterator<Item=&'a str> + 'static, pad_lef
 /// sequence: sequence of items to pad, in the form of an Iterator of string slices.
 /// left_pad_symbol: the padding symbol to prepend
 /// n: the n in n-grams; so for bigrams set to 2, etc
-pub fn pad_sequence_left<'a>(sequence: impl Iterator<Item=&'a str> + 'static, left_pad_symbol: &'static str, n: usize) -> impl Iterator<Item=&'a str> {
-    Padder::new(Box::new(sequence), true, left_pad_symbol, false, "", n)
+pub fn pad_sequence_left<'a>(sequence: impl Iterator<Item=&'a &'a str> + 'a, left_pad_symbol: &'a &'a str, n: usize) -> impl Iterator<Item=&'a &'a str> {
+    Padder::new(Box::new(sequence), true, left_pad_symbol, false, &"", n)
 }
 
 /// Returns a padded sequence of items before ngram extraction, right-padding only. Convenience function that prevents useless arguments
@@ -29,8 +28,8 @@ pub fn pad_sequence_left<'a>(sequence: impl Iterator<Item=&'a str> + 'static, le
 /// pad_right: if set to true, appends a padding symbol after the sentence
 /// right_pad_symbol: the padding symbol to append
 /// n: the n in n-grams; so for bigrams set to 2, etc
-pub fn pad_sequence_right<'a>(sequence: impl Iterator<Item=&'a str> + 'static, right_pad_symbol: &'static str, n: usize) -> impl Iterator<Item=&'a str> + 'a {
-    Padder::new(Box::new(sequence), false, "", true, right_pad_symbol, n)
+pub fn pad_sequence_right<'a>(sequence: impl Iterator<Item=&'a &'a str> + 'a, right_pad_symbol: &'a &'a str, n: usize) -> impl Iterator<Item=&'a &'a str> + 'a {
+    Padder::new(Box::new(sequence), false, &"", true, right_pad_symbol, n)
 }
 
 /// Return the ngrams generated from a sequence of items, as an iterator.
@@ -74,44 +73,44 @@ pub fn flatten<'a>(ngrams: impl Iterator<Item=Box<dyn Iterator<Item=&'a &'a str>
 
 #[cfg(test)]
 mod tests {
-    use std::slice::Iter;
     use super::*;
+    use crate::test::*;
 
     #[test]
     fn test_pad_both_ends_default_n2() {
-        let text = vec!["a", "b", "c"].into_iter();
-        let padded = pad_sequence(text, true, "<s>", true, "</s>", 2);
-        should_be_equal_lists2(padded, vec!["<s>", "a", "b", "c", "</s>"]);
+        let text = vec!["a", "b", "c"];
+        let padded = pad_sequence(text.iter(), true, &"<s>", true, &"</s>", 2);
+        should_be_equal_lists(padded, vec!["<s>", "a", "b", "c", "</s>"]);
     }
 
     #[test]
     fn test_pad_left() {
-        let text = vec!["a", "b", "c"].into_iter();
-        let padded = pad_sequence_left(text, "<s>", 2);
-        should_be_equal_lists2(padded, vec!["<s>", "a", "b", "c"]);
+        let text = vec!["a", "b", "c"];
+        let padded = pad_sequence_left(text.iter(), &"<s>", 2);
+        should_be_equal_lists(padded, vec!["<s>", "a", "b", "c"]);
     }
 
     #[test]
     fn test_pad_right() {
-        let text = vec!["a", "b", "c"].into_iter();
-        let padded = pad_sequence_right(text, "</s>", 2);
+        let text = vec!["a", "b", "c"];
+        let padded = pad_sequence_right(text.iter(), &"</s>", 2);
 
-        should_be_equal_lists2(padded, vec!["a", "b", "c", "</s>"]);
+        should_be_equal_lists(padded, vec!["a", "b", "c", "</s>"]);
     }
 
     #[test]
     fn test_pad_both_ends_default_n_eq_3() {
-        let text = vec!["a", "b", "c"].into_iter();
-        let padded = pad_sequence(text, true, "<s>", true, "</s>", 3);
-        should_be_equal_lists2(padded, vec!["<s>", "<s>", "a", "b", "c", "</s>", "</s>"]);
+        let text = vec!["a", "b", "c"];
+        let padded = pad_sequence(text.iter(), true, &"<s>", true, &"</s>", 3);
+        should_be_equal_lists(padded, vec!["<s>", "<s>", "a", "b", "c", "</s>", "</s>"]);
     }
 
     #[test]
     fn test_pad_both_ends_non_default_symbols() {
-        let text = vec!["a", "b", "c"].into_iter();
-        let padded = pad_sequence(text, true, "left", true, "right", 2);
+        let text = vec!["a", "b", "c"];
+        let padded = pad_sequence(text.iter(), true, &"left", true, &"right", 2);
 
-        should_be_equal_lists2(padded, vec!["left", "a", "b", "c", "right"]);
+        should_be_equal_lists(padded, vec!["left", "a", "b", "c", "right"]);
     }
 
     #[test]
@@ -159,7 +158,7 @@ mod tests {
         let bigram1 = vec!["a", "b"];
         let expected = vec![bigram1.iter()];
 
-        should_be_equal_list_of_lists(&mut bigrams, expected)
+        should_be_equal_list_of_lists(&mut bigrams, expected);
     }
 
 
@@ -175,7 +174,7 @@ mod tests {
         let gram6 = vec!["c", "d"];
         let expected = vec![gram1.iter(), gram2.iter(), gram3.iter(), gram4.iter(), gram5.iter(), gram6.iter()];
 
-        should_be_equal_list_of_lists(&mut bigrams, expected)
+        should_be_equal_list_of_lists(&mut bigrams, expected);
     }
 
     #[test]
@@ -193,7 +192,7 @@ mod tests {
         let gram9 = vec!["c", "d", "e"];
         let expected = vec![gram1.iter(), gram2.iter(), gram3.iter(), gram4.iter(), gram5.iter(), gram6.iter(), gram7.iter(), gram8.iter(), gram9.iter()];
 
-        should_be_equal_list_of_lists(&mut bigrams, expected)
+        should_be_equal_list_of_lists(&mut bigrams, expected);
     }
 
     #[test]
@@ -203,25 +202,4 @@ mod tests {
 
         should_be_equal_lists(flatten(everygrams(sequence.iter(), 3)), expected);
     }
-
-    fn should_be_equal_list_of_lists<'a>(actual: &mut impl Iterator<Item=impl Iterator<Item=&'a &'a str>>, expected: Vec<Iter<&'a str>>) {
-        for (actual_outer, expected_outer) in actual.zip(expected.into_iter()) {
-            for (actual_inner, expected_inner) in actual_outer.zip(expected_outer) {
-                // println!("{} {}", actual_inner, expected_inner);
-                assert_eq!(actual_inner, expected_inner);
-            }
-        }
-    }
-
-    fn should_be_equal_lists<'a>(left: impl Iterator<Item=&'a &'a str>, right: Vec<&'a str>) {
-        for (left, right) in left.zip(right.into_iter()) {
-            assert_eq!(*left, right);
-        }
-    }
-
-    fn should_be_equal_lists2<'a>(left: impl Iterator<Item=&'a str>, right: Vec<&'a str>) {
-        for (left, right) in left.zip(right.into_iter()) {
-            assert_eq!(left, right);
-        }
-    }
 }
\ No newline at end of file
diff --git a/src/util/ngrams.rs b/src/util/ngrams.rs
index edfeb52..e4d6ddc 100644
--- a/src/util/ngrams.rs
+++ b/src/util/ngrams.rs
@@ -82,7 +82,12 @@ impl<'a> Iterator for EveryGramSequenceIter<'a> {
             let maybe_next = self.sequence.next();
             if maybe_next.is_some() {
                 self.current_ngram.push(&maybe_next.unwrap());
-            } else { return None; }
+            } else {
+                self.n = 0; // not pretty, but ensures that the following next will be the last
+                if self.current_ngram.len() == 0 {
+                    return None;
+                }
+            }
         }
 
         return Some(Box::new(self.current_ngram.clone().into_iter().take(self.current_size)));
diff --git a/src/util/padding.rs b/src/util/padding.rs
index 78d6572..6311629 100644
--- a/src/util/padding.rs
+++ b/src/util/padding.rs
@@ -1,16 +1,16 @@
 pub struct Padder<'a> {
     n: usize,
-    text: Box<dyn Iterator<Item=&'a str>>,
+    text: Box<dyn Iterator<Item=&'a &'a str> + 'a>,
     pad_left: bool,
     left_index: isize,
-    left_pad_symbol: &'static str,
+    left_pad_symbol: &'a &'a str,
     pad_right: bool,
     right_index: isize,
-    right_pad_symbol: &'static str,
+    right_pad_symbol: &'a &'a str,
 }
 
 impl<'a> Iterator for Padder<'a> {
-    type Item = &'a str;
+    type Item = &'a &'a str;
 
     fn next(&mut self) -> Option<Self::Item> {
         if self.pad_left && self.left_index < self.n as isize {
@@ -33,8 +33,8 @@ impl<'a> Iterator for Padder<'a> {
 }
 
 impl<'a> Padder<'a> {
-    pub(crate) fn new(text: Box<dyn Iterator<Item=&'a str>>, pad_left: bool, left_pad_symbol: &'static str,
-                      pad_right: bool, right_pad_symbol: &'static str, n: usize, ) -> Self {
+    pub(crate) fn new(text: Box<dyn Iterator<Item=&'a &'a str> + 'a>, pad_left: bool, left_pad_symbol:&'a &'a str,
+                      pad_right: bool, right_pad_symbol: &'a &'a str, n: usize, ) -> Self {
         Self { text, n, pad_left, left_index: 1, left_pad_symbol, pad_right, right_index: 1, right_pad_symbol }
     }
 }