diff --git a/CHANGELOG.md b/CHANGELOG.md
index 708b3ed0..34269921 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,7 +21,7 @@ All Notable changes to `Csv` will be documented in this file
     - `League\Csv\HTMLConverter` converts CSV records into HTML table.
 - Improved Exception handling
     - `League\Csv\Exception` the default exception
-    - `League\Csv\Exception\CannotInsertRecord`
+    - `League\Csv\CannotInsertRecord`
 - Improved CSV document output
     - `League\Csv\AbstractCsv::chunk` method to output the CSV document in chunk
     - `League\Csv\bom_match` function to detect BOM sequence in a given string
@@ -32,7 +32,7 @@ All Notable changes to `Csv` will be documented in this file
     - `League\Csv\Writer::setFlushThreshold`
     - `League\Csv\Writer::getFlushThreshold`
 - Improve RFC4180 compliance
-    - `League\Csv\RFC4180FieldFormatter` to format field according to RFC4180 rules
+    - `League\Csv\RFC4180Field` to format field according to RFC4180 rules
 
 ### Deprecated
 
diff --git a/src/AbstractCsv.php b/src/AbstractCsv.php
index dbfb79b9..e8b0cc52 100644
--- a/src/AbstractCsv.php
+++ b/src/AbstractCsv.php
@@ -28,8 +28,6 @@
  */
 abstract class AbstractCsv implements ByteSequence
 {
-    use ValidatorTrait;
-
     /**
      * The stream filter mode (read or write)
      *
@@ -325,16 +323,24 @@ public function output(string $filename = null): int
      *
      * @param string $delimiter
      *
+     * @throws Exception If the Csv control character is not one character only.
+     *
      * @return static
      */
     public function setDelimiter(string $delimiter): self
     {
-        if ($delimiter != $this->delimiter) {
-            $this->delimiter = $this->filterControl($delimiter, 'delimiter', __METHOD__);
+        if ($delimiter === $this->delimiter) {
+            return $this;
+        }
+
+        if (1 === strlen($delimiter)) {
+            $this->delimiter = $delimiter;
             $this->resetProperties();
+
+            return $this;
         }
 
-        return $this;
+        throw new Exception(sprintf('%s() expects delimiter to be a single character %s given', __METHOD__, $delimiter));
     }
 
     /**
@@ -349,16 +355,24 @@ protected function resetProperties()
      *
      * @param string $enclosure
      *
+     * @throws Exception If the Csv control character is not one character only.
+     *
      * @return static
      */
     public function setEnclosure(string $enclosure): self
     {
-        if ($enclosure != $this->enclosure) {
-            $this->enclosure = $this->filterControl($enclosure, 'enclosure', __METHOD__);
+        if ($enclosure === $this->enclosure) {
+            return $this;
+        }
+
+        if (1 === strlen($enclosure)) {
+            $this->enclosure = $enclosure;
             $this->resetProperties();
+
+            return $this;
         }
 
-        return $this;
+        throw new Exception(sprintf('%s() expects enclosure to be a single character %s given', __METHOD__, $enclosure));
     }
 
     /**
@@ -366,16 +380,24 @@ public function setEnclosure(string $enclosure): self
      *
      * @param string $escape
      *
+     * @throws Exception If the Csv control character is not one character only.
+     *
      * @return static
      */
     public function setEscape(string $escape): self
     {
-        if ($escape != $this->escape) {
-            $this->escape = $this->filterControl($escape, 'escape', __METHOD__);
+        if ($escape === $this->escape) {
+            return $this;
+        }
+
+        if (1 === strlen($escape)) {
+            $this->escape = $escape;
             $this->resetProperties();
+
+            return $this;
         }
 
-        return $this;
+        throw new Exception(sprintf('%s() expects escape to be a single character %s given', __METHOD__, $escape));
     }
 
     /**
diff --git a/src/Reader.php b/src/Reader.php
index 694ca084..8934ba5f 100644
--- a/src/Reader.php
+++ b/src/Reader.php
@@ -21,6 +21,7 @@
 use IteratorAggregate;
 use JsonSerializable;
 use SplFileObject;
+use TypeError;
 
 /**
  * A class to manage records selection from a CSV document
@@ -308,12 +309,21 @@ protected function stripBOM(Iterator $iterator, string $bom): Iterator
      */
     public function setHeaderOffset($offset): self
     {
-        $this->filterNullableInteger($offset, 0, __METHOD__.'() expects the header offset index to be a positive integer or 0');
-        if ($offset !== $this->header_offset) {
-            $this->header_offset = $offset;
-            $this->resetProperties();
+        if ($offset === $this->header_offset) {
+            return $this;
         }
 
+        if (!is_nullable_int($offset)) {
+            throw new TypeError(sprintf(__METHOD__.'() expects 1 Argument to be null or an integer %s given', gettype($offset)));
+        }
+
+        if (null !== $offset && 0 > $offset) {
+            throw new Exception(__METHOD__.'() expects 1 Argument to be greater or equal to 0');
+        }
+
+        $this->header_offset = $offset;
+        $this->resetProperties();
+
         return $this;
     }
 
diff --git a/src/ResultSet.php b/src/ResultSet.php
index e3358bc9..5305ffef 100644
--- a/src/ResultSet.php
+++ b/src/ResultSet.php
@@ -169,10 +169,7 @@ public function fetchColumn($index = 0): Generator
      */
     protected function getColumnIndex($field, string $error_message)
     {
-        $method = 'getColumnIndexByKey';
-        if (is_string($field)) {
-            $method = 'getColumnIndexByValue';
-        }
+        $method = is_string($field) ? 'getColumnIndexByValue' : 'getColumnIndexByKey';
 
         return $this->$method($field, $error_message);
     }
diff --git a/src/Stream.php b/src/Stream.php
index 57eae3b8..4e6602d9 100644
--- a/src/Stream.php
+++ b/src/Stream.php
@@ -30,8 +30,6 @@
  */
 class Stream implements SeekableIterator
 {
-    use ValidatorTrait;
-
     /**
      * Attached filters
      *
@@ -238,9 +236,36 @@ public function appendFilter(string $filtername, int $read_write, $params = null
      */
     public function setCsvControl(string $delimiter = ',', string $enclosure = '"', string $escape = '\\')
     {
-        $this->delimiter = $this->filterControl($delimiter, 'delimiter', __METHOD__);
-        $this->enclosure = $this->filterControl($enclosure, 'enclosure', __METHOD__);
-        $this->escape = $this->filterControl($escape, 'escape', __METHOD__);
+        list($this->delimiter, $this->enclosure, $this->escape) = $this->filterControl($delimiter, $enclosure, $escape, __METHOD__);
+    }
+
+    /**
+     * Filter Csv control characters
+     *
+     * @param string $delimiter CSV delimiter character
+     * @param string $enclosure CSV enclosure character
+     * @param string $escape    CSV escape character
+     * @param string $caller    public API method calling the method
+     *
+     * @throws Exception If the Csv control character is not one character only.
+     *
+     * @return array
+     */
+    protected function filterControl(string $delimiter, string $enclosure, string $escape, string $caller): array
+    {
+        if (1 !== strlen($delimiter)) {
+            throw new Exception(sprintf('%s() expects delimiter to be a single character', $caller));
+        }
+
+        if (1 !== strlen($enclosure)) {
+            throw new Exception(sprintf('%s() expects enclosure to be a single character', $caller));
+        }
+
+        if (1 !== strlen($escape)) {
+            throw new Exception(sprintf('%s() expects escape to be a single character', $caller));
+        }
+
+        return [$delimiter, $enclosure, $escape];
     }
 
     /**
@@ -281,13 +306,9 @@ public function setFlags(int $flags)
      */
     public function fputcsv(array $fields, string $delimiter = ',', string $enclosure = '"', string $escape = '\\')
     {
-        return fputcsv(
-            $this->stream,
-            $fields,
-            $this->filterControl($delimiter, 'delimiter', __METHOD__),
-            $this->filterControl($enclosure, 'enclosure', __METHOD__),
-            $this->filterControl($escape, 'escape', __METHOD__)
-        );
+        $controls =  $this->filterControl($delimiter, $enclosure, $escape, __METHOD__);
+
+        return fputcsv($this->stream, $fields, ...$controls);
     }
 
     /**
diff --git a/src/ValidatorTrait.php b/src/ValidatorTrait.php
deleted file mode 100644
index 2283015e..00000000
--- a/src/ValidatorTrait.php
+++ /dev/null
@@ -1,75 +0,0 @@
-<?php
-/**
-* This file is part of the League.csv library
-*
-* @license http://opensource.org/licenses/MIT
-* @link https://github.com/thephpleague/csv/
-* @version 9.0.0
-* @package League.csv
-*
-* For the full copyright and license information, please view the LICENSE
-* file that was distributed with this source code.
-*/
-declare(strict_types=1);
-
-namespace League\Csv;
-
-use TypeError;
-
-/**
- * A trait to validate input variables
- *
- * @package  League.csv
- * @since    9.0.0
- * @author   Ignace Nyamagana Butera <nyamsprod@gmail.com>
- * @internal Use to validate incoming data
- */
-trait ValidatorTrait
-{
-    /**
-     * Filter Csv control character
-     *
-     * @param string $char   Csv control character
-     * @param string $type   Csv control character type
-     * @param string $caller public API method calling the method
-     *
-     * @throws Exception If the Csv control character is not one character only.
-     *
-     * @return string
-     */
-    protected function filterControl(string $char, string $type, string $caller): string
-    {
-        if (1 == strlen($char)) {
-            return $char;
-        }
-
-        throw new Exception(sprintf('%s() expects %s to be a single character %s given', $caller, $type, $char));
-    }
-
-    /**
-     * Filter Nullable Integer with mininal range check
-     *
-     * @see https://wiki.php.net/rfc/nullable_types
-     *
-     * @param int|null $value
-     * @param int      $min_range
-     * @param string   $error_message
-     *
-     * @throws TypError  if value is not a integer or null
-     * @throws Exception if value is not in a valid int range
-     */
-    protected function filterNullableInteger($value, int $min_range, string $error_message)
-    {
-        if (null === $value) {
-            return;
-        }
-
-        if (!is_int($value)) {
-            throw new TypeError(sprintf('Expected argument to be null or a integer %s given', gettype($value)));
-        }
-
-        if ($value < $min_range) {
-            throw new Exception($error_message);
-        }
-    }
-}
diff --git a/src/Writer.php b/src/Writer.php
index 58befd5a..ae5c5f0d 100644
--- a/src/Writer.php
+++ b/src/Writer.php
@@ -241,17 +241,22 @@ public function setNewline(string $newline): self
      */
     public function setFlushThreshold($threshold): self
     {
-        $this->filterNullableInteger($threshold, 1, __METHOD__.'() expects 1 Argument to be null or a valid integer greater or equal to 1');
         if ($threshold === $this->flush_threshold) {
             return $this;
         }
 
-        $this->flush_threshold = $threshold;
-        if (0 < $this->flush_counter) {
-            $this->flush_counter = 0;
-            $this->document->fflush();
+        if (!is_nullable_int($threshold)) {
+            throw new TypeError(sprintf(__METHOD__.'() expects 1 Argument to be null or an integer %s given', gettype($threshold)));
+        }
+
+        if (null !== $threshold && 1 >= $threshold) {
+            throw new Exception(__METHOD__.'() expects 1 Argument to be null or a valid integer greater or equal to 1');
         }
 
+        $this->flush_threshold = $threshold;
+        $this->flush_counter = 0;
+        $this->document->fflush();
+
         return $this;
     }
 }
diff --git a/src/functions.php b/src/functions.php
index ab17bbfd..a50cb96e 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -78,11 +78,11 @@ function delimiter_detect(Reader $csv, array $delimiters, int $limit = 1): array
 
 if (!function_exists('\is_iterable')) {
     /**
-     * Tell whether the contents of the variable is iterable
+     * Tell whether the content of the variable is iterable
      *
      * @see http://php.net/manual/en/function.is-iterable.php
      *
-     * @param array|Traversable $iterable
+     * @param mixed $iterable
      *
      * @return bool
      */
@@ -91,3 +91,17 @@ function is_iterable($iterable): bool
         return is_array($iterable) || $iterable instanceof Traversable;
     }
 }
+
+/**
+ * Tell whether the content of the variable is an int or null
+ *
+ * @see https://wiki.php.net/rfc/nullable_types
+ *
+ * @param mixed $value
+ *
+ * @return bool
+ */
+function is_nullable_int($value): bool
+{
+    return null === $value || is_int($value);
+}
diff --git a/tests/CsvTest.php b/tests/CsvTest.php
index 5e0c8660..8f144370 100644
--- a/tests/CsvTest.php
+++ b/tests/CsvTest.php
@@ -194,13 +194,13 @@ public function testStreamFilterMode()
     /**
      * @covers ::getDelimiter
      * @covers ::setDelimiter
-     * @covers ::filterControl
      */
     public function testDelimeter()
     {
         $this->expectException(Exception::class);
         $this->csv->setDelimiter('o');
         $this->assertSame('o', $this->csv->getDelimiter());
+        $this->assertSame($this->csv, $this->csv->setDelimiter('o'));
         $this->csv->setDelimiter('foo');
     }
 
@@ -251,6 +251,7 @@ public function testEscape()
         $this->expectException(Exception::class);
         $this->csv->setEscape('o');
         $this->assertSame('o', $this->csv->getEscape());
+        $this->assertSame($this->csv, $this->csv->setEscape('o'));
 
         $this->csv->setEscape('foo');
     }
@@ -264,6 +265,7 @@ public function testEnclosure()
         $this->expectException(Exception::class);
         $this->csv->setEnclosure('o');
         $this->assertSame('o', $this->csv->getEnclosure());
+        $this->assertSame($this->csv, $this->csv->setEnclosure('o'));
 
         $this->csv->setEnclosure('foo');
     }
diff --git a/tests/ReaderTest.php b/tests/ReaderTest.php
index dabac958..090650e8 100644
--- a/tests/ReaderTest.php
+++ b/tests/ReaderTest.php
@@ -298,8 +298,8 @@ public function testGetHeaderThrowsException()
     }
 
     /**
-     * @covers ::setHeader
-     * @covers ::filterNullableInteger
+     * @covers ::setHeaderOffset
+     * @covers \League\Csv\is_nullable_int
      */
     public function testSetHeaderThrowsExceptionOnWrongInput()
     {
@@ -308,8 +308,7 @@ public function testSetHeaderThrowsExceptionOnWrongInput()
     }
 
     /**
-     * @covers ::setHeader
-     * @covers ::filterNullableInteger
+     * @covers ::setHeaderOffset
      */
     public function testSetHeaderThrowsExceptionOnWrongInputRange()
     {
diff --git a/tests/StreamTest.php b/tests/StreamTest.php
index ef75918c..41a51b39 100644
--- a/tests/StreamTest.php
+++ b/tests/StreamTest.php
@@ -88,6 +88,8 @@ public function testCreateStreamFromPathWithContext()
 
     /**
      * @covers ::fputcsv
+     * @covers ::filterControl
+     *
      * @dataProvider fputcsvProvider
      *
      * @param string $delimiter
@@ -140,4 +142,20 @@ public function testSeek()
         $doc->seek(1);
         $this->assertSame(['Aaron', '55', 'M', '2004'], $doc->current());
     }
+
+    /**
+     * @covers ::setCsvControl
+     * @covers ::getCsvControl
+     * @covers ::filterControl
+     */
+    public function testCsvControl()
+    {
+        $doc = Stream::createFromString('foo,bar');
+        $this->assertSame([',', '"', '\\'], $doc->getCsvControl());
+        $expected = [';', '|', '"'];
+        $doc->setCsvControl(...$expected);
+        $this->assertSame($expected, $doc->getCsvControl());
+        $this->expectException(Exception::class);
+        $doc->setCsvControl(...['foo']);
+    }
 }
diff --git a/tests/WriterTest.php b/tests/WriterTest.php
index f07d526c..d46fa002 100644
--- a/tests/WriterTest.php
+++ b/tests/WriterTest.php
@@ -37,7 +37,6 @@ public function tearDown()
     /**
      * @covers ::getFlushThreshold
      * @covers ::setFlushThreshold
-     * @covers ::filterNullableInteger
      */
     public function testflushThreshold()
     {
@@ -50,7 +49,7 @@ public function testflushThreshold()
 
     /**
      * @covers ::setFlushThreshold
-     * @covers ::filterNullableInteger
+     * @covers \League\Csv\is_nullable_int
      */
     public function testflushThresholdThrowsTypeError()
     {