diff -r 96b8395ca393 nml/free_number_list.py
--- a/nml/free_number_list.py Thu May 18 20:58:11 2017 +0200
+++ b/nml/free_number_list.py Mon Jun 19 20:26:10 2017 +0200
@@ -69,7 +69,7 @@
@return: Some free number.
"""
assert len(self.states) > 0
- if self.free_numbers == 0:
+ if len(self.free_numbers) == 0:
raise generic.ScriptError(self.exception, pos)
num = self.free_numbers.pop()
self.states[-1].append(num)