Remove unused EOF error and use comma ok syntax

consumer.go

@@ -74,19 +74,19 @@ func (iter *Iterator) Reduce(initialState interface{}, f ReduceFunc) interface{}
 }
 
 // Find consumes elements and returns the first element that satisfies `f` (returning `true`).
-// Returns an `EOF` error if no element is found.
-func (iter *Iterator) Find(f PredicateFunc) (interface{}, error) {
+// Returns `nil, false` if no element is found.
+func (iter *Iterator) Find(f PredicateFunc) (interface{}, bool) {
 	var elem interface{}
-	err := End()
+	ok := false
 	iter.iter(func(element interface{}) bool {
 		if f(element) {
 			elem = element
-			err = nil
+			ok = true
 			return false
 		}
 		return true
 	})
-	return elem, err
+	return elem, ok
 }
 
 // Min consumes elements and returns the minimum element.
@@ -156,21 +156,21 @@ func (iter *Iterator) Last() interface{} {
 }
 
 // Nth consumes elements and returns the `n`th element. Indexing starts from `0`.
-// Returns an `EOF` error if the length of iterator is less than `n`.
-func (iter *Iterator) Nth(n int) (interface{}, error) {
+// Returns an nil, false` if the length of iterator is less than `n`.
+func (iter *Iterator) Nth(n int) (interface{}, bool) {
 	var nth interface{}
-	err := End()
+	ok := false
 	index := 0
 	iter.iter(func(element interface{}) bool {
 		if index == n {
 			nth = element
-			err = nil
+			ok = true
 			return false
 		}
 		index++
 		return true
 	})
-	return nth, err
+	return nth, ok
 }
 
 // Count consumes elements and returns the length of elements.

consumer_test.go

@@ -49,19 +49,19 @@ func TestFind(t *testing.T) {
 	gen := generator.NewSlice(elements)
 	iterator := goterator.New(gen)
 
-	three, err := iterator.Find(func(e interface{}) bool {
+	three, ok := iterator.Find(func(e interface{}) bool {
 		return e.(int) == 3
 	})
 	assert.Equal(3, three)
-	assert.Nil(err)
+	assert.True(ok)
 
 	gen = generator.NewSlice(elements)
 	iterator = goterator.New(gen)
 
-	_, err = iterator.Find(func(e interface{}) bool {
+	_, ok = iterator.Find(func(e interface{}) bool {
 		return e.(int) == 6
 	})
-	assert.NotNil(err)
+	assert.False(ok)
 }
 
 func TestMin(t *testing.T) {
@@ -160,15 +160,15 @@ func TestNth(t *testing.T) {
 	gen := generator.NewSlice(elements)
 	iterator := goterator.New(gen)
 
-	nth, err := iterator.Nth(5)
+	nth, ok := iterator.Nth(5)
 	assert.Equal(7, nth)
-	assert.Nil(err)
+	assert.True(ok)
 
 	gen = generator.NewSlice(elements)
 	iterator = goterator.New(gen)
 
-	_, err = iterator.Nth(len(elements))
-	assert.NotNil(err)
+	_, ok = iterator.Nth(len(elements))
+	assert.False(ok)
 }
 
 func TestCount(t *testing.T) {