Use 'return', not 'yield'

Single line

lart.py

@@ -93,7 +93,7 @@ class Lart(BotPlugin):
         if len(args) < 2:
             return "**Usage**: !lart edit <id> <pattern>"
         if '{}' not in args:
-            yield "**Error**: '{}' not in message"
+            return "**Error**: '{}' not in message"
 
         try:
             i = int(args[0])
@@ -101,6 +101,6 @@ class Lart(BotPlugin):
             self.larts[i] = text
             return "Changed lart {} to '{}'".format(i, text)
         except IndexError:
-            yield "**Error**: Lart {} not in database".format(i)
+            return "**Error**: Lart {} not in database".format(i)
         except ValueError:
-            yield "**Error**: ID given couldn't be converted to an integer"
+            return "**Error**: ID given couldn't be converted to an integer"