From d61f30b62c605e35e8b46e08f1ace6c16e708466 Mon Sep 17 00:00:00 2001
From: B_Ries <benjamin-ries@outlook.com>
Date: Thu, 22 Apr 2021 11:45:06 +0200
Subject: [PATCH] Update imd_blocks.py

just a minor save
---
 pygromos/files/blocks/imd_blocks.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pygromos/files/blocks/imd_blocks.py b/pygromos/files/blocks/imd_blocks.py
index 4ea5691f..95d24855 100644
--- a/pygromos/files/blocks/imd_blocks.py
+++ b/pygromos/files/blocks/imd_blocks.py
@@ -607,6 +607,9 @@ def block_to_string(self) -> str:
         result += "  " + str(self.ALGORITHM) + "\n"
 
         if(self.ALGORITHM == "2"):
+            if(self.NUM is None):
+                raise Exception("You need to specify the NUM parameter for MULTIBATH if ALGORITHM is 2!")
+               
             result += "# " + "\t".join(self._order[0][1]) + "\n"
             result += "  " + str(self.NUM) + "\n"