Update app.py

app.py

@@ -6,7 +6,7 @@ langtext = st.text_area("language code", "en")
 found = langcodes.find(langtext)
 display = found.display_name()
 
-if tag_is_valid('langtext'):
+if langcodes.tag_is_valid('langtext'):
   st.write(f"{langtext} is a valid BCP-47 language code")  
 else:
   st.write(f"{langtext} is not a valid BCP-47 language code")