Simplify conditions

Author: Luflosi

kitty/boss.py

@@ -58,9 +58,9 @@ def as_text(**kw):
 
     if arg == '@selection':
         return w.text_for_selection()
-    if arg == '@ansi' or arg == '@ansi_screen_scrollback':
+    if arg in ('@ansi', '@ansi_screen_scrollback'):
         return as_text(as_ansi=True, add_history=True)
-    if arg == '@text' or arg == '@screen_scrollback':
+    if arg in ('@text', '@screen_scrollback'):
         return as_text(add_history=True)
     if arg == '@screen':
         return as_text()