Prepare for block level program handling

src/Automata/Storage/ToolMemory.php

@@ -3,6 +3,7 @@
 namespace Automata\Storage;
 
 use Automata\Tool;
+use InvalidArgumentException;
 
 class ToolMemory
 {
@@ -12,6 +13,7 @@ class ToolMemory
 
 	public function save(Tool $tool): void
 	{
+		$this->guardInvalidToolNumber($tool->T);
 		$this->memory[$tool->T] = $tool;
 	}
 
@@ -20,4 +22,13 @@ class ToolMemory
 	{
 		return @$this->memory[$T];
 	}
+
+
+	private function guardInvalidToolNumber(int $T): void
+	{
+		if ($T < 1 || $T > 64) {
+			throw new InvalidArgumentException('Tool number must be in range 1 - 64');
+		}
+	}
+
 }