replace extra (str) -> extras (iterable)

IPython/lib/display.py

@@ -8,7 +8,7 b' from os import walk, sep, fsdecode'
 
 from IPython.core.display import DisplayObject, TextDisplayObject
 
-from typing import Tuple
+from typing import Tuple, Iterable
 
 __all__ = ['Audio', 'IFrame', 'YouTubeVideo', 'VimeoVideo', 'ScribdDocument',
            'FileLink', 'FileLinks', 'Code']
@@ -263,15 +263,18 b' class IFrame(object):'
             src="{src}{params}"
             frameborder="0"
             allowfullscreen
-            {extra}
+            {extras}
         ></iframe>
         """
 
-    def __init__(self, src, width, height, extra="", **kwargs):
+    def __init__(self, src, width, height, extras: Iterable[str] = None, **kwargs):
+        if extras is None:
+            extras = []
+
         self.src = src
         self.width = width
         self.height = height
-        self.extra = extra
+        self.extras = extras
         self.params = kwargs
 
     def _repr_html_(self):
@@ -286,7 +289,7 b' class IFrame(object):'
             width=self.width,
             height=self.height,
             params=params,
-            extra=self.extra,
+            extras=" ".join(self.extras),
         )
 
 
@@ -320,7 +323,7 b' class YouTubeVideo(IFrame):'
         self.id=id
         src = "https://www.youtube.com/embed/{0}".format(id)
         if allow_autoplay:
-            kwargs.update(autoplay=1, extra='allow="autoplay"')
+            kwargs.update(autoplay=1, extras=['allow="autoplay"'])
         super(YouTubeVideo, self).__init__(src, width, height, **kwargs)
 
     def _repr_jpeg_(self):