Disallow year 0

visualizer/parameters.py

@@ -31,6 +31,6 @@ def year_type(s):
     """Type converter for valid years."""
     if s.isdigit():
         val = int(s)
-        if val in range(10000):
+        if val in range(1, 10000):
             return val
     raise ValueError(f'bad year arg: {s!r}')