diff --git a/composer.json b/composer.json
index 01bc304..5c0e58b 100644
--- a/composer.json
+++ b/composer.json
@@ -10,9 +10,9 @@
     ],
     "require": {
         "php": ">=7.4",
+        "ext-ctype": "*",
         "ext-json": "*",
-        "fmizzell/maquina": "^1.1.1",
-        "getdkan/contracts": "^1.1.3"
+        "fmizzell/maquina": "^1.1.1"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.6",
diff --git a/src/Parser/Csv.php b/src/Parser/Csv.php
index 86419b4..3ab70d9 100644
--- a/src/Parser/Csv.php
+++ b/src/Parser/Csv.php
@@ -3,9 +3,8 @@
 
 namespace CsvParser\Parser;
 
-use Contracts\ParserInterface;
-use Maquina\StateMachine\MachineOfMachines;
 use CsvParser\Parser\StateMachine as sm;
+use Maquina\StateMachine\MachineOfMachines;
 
 class Csv implements ParserInterface, \JsonSerializable
 {
@@ -49,7 +48,7 @@ public function __construct($delimiter, $quote, $escape, array $record_end)
         $this->machine->stopRecording();
     }
 
-    public function feed(string $chunk)
+    public function feed(string $chunk): void
     {
         if (strlen($chunk) > 0) {
             $chars = str_split($chunk);
@@ -104,7 +103,7 @@ public function reset(): void
         $this->quoted = false;
     }
 
-    public function finish()
+    public function finish(): void
     {
         // There will be csv strings that do not end in a "end of record" char.
         // This will flush them.
diff --git a/src/Parser/ParserInterface.php b/src/Parser/ParserInterface.php
new file mode 100644
index 0000000..e06055d
--- /dev/null
+++ b/src/Parser/ParserInterface.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace CsvParser\Parser;
+
+/**
+ * Interface for parsing CSV files.
+ */
+interface ParserInterface
+{
+
+    /**
+     * Feed a string into the parser.
+     *
+     * @param string $chunk
+     *   A chunk of the CSV being fed into the parser.
+     */
+    public function feed(string $chunk): void;
+
+    /**
+     * Get a record.
+     *
+     * @return array|null
+     *   The record as an array, or null.
+     */
+    public function getRecord();
+
+    /**
+     * Reset the parser to an initialized state.
+     */
+    public function reset(): void;
+
+    /**
+     * At the end of a run of parsing, ensure there were no errors.
+     *
+     * @throws \Exception
+     *   Throws an exception if the state machine was out of sync with our
+     *   expectations.
+     */
+    public function finish(): void;
+}