Update README.md to include part6

vendor/phpstan/phpdoc-parser/src/Ast/NodeAttributes.php

@@ -0,0 +1,42 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\PhpDocParser\Ast;
+
+use function array_key_exists;
+
+trait NodeAttributes
+{
+
+	/** @var array<string, mixed> */
+	private array $attributes = [];
+
+	/**
+	 * @param mixed $value
+	 */
+	public function setAttribute(string $key, $value): void
+	{
+		if ($value === null) {
+			unset($this->attributes[$key]);
+			return;
+		}
+		$this->attributes[$key] = $value;
+	}
+
+	public function hasAttribute(string $key): bool
+	{
+		return array_key_exists($key, $this->attributes);
+	}
+
+	/**
+	 * @return mixed
+	 */
+	public function getAttribute(string $key)
+	{
+		if ($this->hasAttribute($key)) {
+			return $this->attributes[$key];
+		}
+
+		return null;
+	}
+
+}