Fix get_doc_string.

Author: jakeichikawasalesforce

tabpy/tabpy_tools/custom_query_object.py

@@ -75,10 +75,13 @@ def query(self, *args, **kwargs):
     def get_doc_string(self):
         """Get doc string from customized query"""
         default_docstring = "-- no docstring found in query function --"
-        if platform.system() == "Windows" and sys.maxsize <= 2**32:
+
+        # TODO: fix docstring parsing on Windows systems
+        if sys.platform == 'win32':
             return default_docstring
-        else:
-            return inspect.getdoc(self.custom_query) or default_docstring
+
+        ds = getattr(self.custom_query, '__doc__', None)
+        return ds if ds and isinstance(ds, str) else default_docstring
 
     def get_methods(self):
         return [self.get_query_method()]