fixes #569

Author: jph00

fastcore/xml.py

@@ -59,8 +59,9 @@ def xt(tag:str, *c, **kw):
 
 # %% ../nbs/11_xml.ipynb 13
 def _to_attr(k,v):
-    if v==True: return str(k)
-    if v==False: return ''
+    if isinstance(v,bool):
+        if v==True : return str(k)
+        if v==False: return ''
     return f'{k}="{escape(str(v), quote=False)}"'
 
 # %% ../nbs/11_xml.ipynb 14