fix bug with add_modis

Author: mdtanker

src/polartoolkit/maps.py

@@ -778,10 +778,12 @@ def add_modis(
             colormap to use for MODIS imagery, by default "grayC"
         """
 
-        if self.epsg == "3413" and version is None:
-            version = "500m"
-        elif self.epsg == "3031" and version is None:
-            version = "750m"
+        if self.epsg == "3413":
+            if version is None:
+                version = "500m"
+        elif self.epsg == "3031":
+            if version is None:
+                version = "750m"
         else:
             msg = "`add_modis` only supports EPSG:3031 and EPSG:3413."
             raise NotImplementedError(msg)