a little useful function addition

.gitignore

@@ -0,0 +1,26 @@
+bin*/*
+server.lock
+*.log
+
+# Common IDEs
+.idea/
+nbproject/*
+
+# Windows image file caches
+Thumbs.db
+
+# Folder config file
+Desktop.ini
+
+# Mac crap
+.DS_Store
+/nbproject/private/
+
+# Composer
+vendor/*
+
+# Tests
+tests/*
+
+virion.php
+virion_stub.php

src/JackMD/Citation/Command/BaseCommand.php

@@ -127,6 +127,16 @@ public function registerSubCommand(SubCommand $command): void{
 		}
 	}
 
+	/**
+	 * @param array $args
+	 * @return bool
+	 */
+	public function subCommandExists(array $args): bool{
+		$subCommand = strtolower(array_shift($args));
+
+		return isset($this->subCommands[$subCommand]) || isset($this->aliasSubCommands[$subCommand]);
+	}
+
 	/**
 	 * @param CommandSender $sender
 	 * @param array         $args