prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Completion Example Error.
  <!--
  This issue tracker is a tool to address bugs in Click itself. Please use
  Pallets Discord or Stack Overflow for questions about your own code.
  
  Replace this comment with a clear outline of what the bug is.
  -->
  
  <!--
  Describe how to replicate the bug.
  
  Include a minimal reproducible example that demonstrates the bug.
  Include the full traceback if there was an exception.
  -->
  
  When running completion example, try to do completion with completion `group select-user` and it will produce the following error.
  
  ```
  completion group select-user bTraceback (most recent call last):      
    File "/Users/thomas/.pyenv/versions/3.8.5/bin/completion", line 11, in <module>
      load_entry_point('click-example-completion', 'console_scripts', 'completion')()
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py", line 1137, in __call__
      return self.main(*args, **kwargs)
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py", line 1057, in main
      self._main_shell_completion(extra, prog_name, complete_var)
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py", line 1132, in _main_shell_completion
      rv = shell_complete(self, ctx_args, prog_name, complete_var, instruction)
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py", line 49, in shell_complete
      echo(comp.complete())
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py", line 291, in complete
      completions = self.get_completions(args, incomplete)
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py", line 273, in get_completions
      return obj.shell_complete(ctx, incomplete)
    File "/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py", line 2403, in shell_complete
      if results and isinstance(results[0], str):
  TypeError: 'generator' object is not subscriptable
  ```
  
  <!--
  Describe the expected behavior that should have happened but didn't.
  -->
  
  Environment:
  
  - Python version:
  - Click version:
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `examples/completion/completion.py`
  Content:
  ```
  1 import os
  2 
  3 import click
  4 from click.shell_completion import CompletionItem
  5 
  6 
  7 @click.group()
  8 def cli():
  9     pass
  10 
  11 
  12 @cli.command()
  13 @click.option("--dir", type=click.Path(file_okay=False))
  14 def ls(dir):
  15     click.echo("\n".join(os.listdir(dir)))
  16 
  17 
  18 def get_env_vars(ctx, param, incomplete):
  19     # Returning a list of values is a shortcut to returning a list of
  20     # CompletionItem(value).
  21     return [k for k in os.environ if incomplete in k]
  22 
  23 
  24 @cli.command(help="A command to print environment variables")
  25 @click.argument("envvar", shell_complete=get_env_vars)
  26 def show_env(envvar):
  27     click.echo(f"Environment variable: {envvar}")
  28     click.echo(f"Value: {os.environ[envvar]}")
  29 
  30 
  31 @cli.group(help="A group that holds a subcommand")
  32 def group():
  33     pass
  34 
  35 
  36 def list_users(ctx, param, incomplete):
  37     # You can generate completions with help strings by returning a list
  38     # of CompletionItem. You can match on whatever you want, including
  39     # the help.
  40     items = [("bob", "butcher"), ("alice", "baker"), ("jerry", "candlestick maker")]
  41 
  42     for value, help in items:
  43         if incomplete in value or incomplete in help:
  44             yield CompletionItem(value, help=help)
  45 
  46 
  47 @group.command(help="Choose a user")
  48 @click.argument("user", shell_complete=list_users)
  49 def select_user(user):
  50     click.echo(f"Chosen user is {user}")
  51 
  52 
  53 cli.add_command(group)
  54
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/examples/completion/completion.py b/examples/completion/completion.py
  --- a/examples/completion/completion.py
  +++ b/examples/completion/completion.py
  @@ -38,10 +38,13 @@
       # of CompletionItem. You can match on whatever you want, including
       # the help.
       items = [("bob", "butcher"), ("alice", "baker"), ("jerry", "candlestick maker")]
  +    out = []
   
       for value, help in items:
           if incomplete in value or incomplete in help:
  -            yield CompletionItem(value, help=help)
  +            out.append(CompletionItem(value, help=help))
  +
  +    return out
   
   
   @group.command(help="Choose a user")
  
verification_info: {"golden_diff": "diff --git a/examples/completion/completion.py b/examples/completion/completion.py\n--- a/examples/completion/completion.py\n+++ b/examples/completion/completion.py\n@@ -38,10 +38,13 @@\n     # of CompletionItem. You can match on whatever you want, including\n     # the help.\n     items = [(\"bob\", \"butcher\"), (\"alice\", \"baker\"), (\"jerry\", \"candlestick maker\")]\n+    out = []\n \n     for value, help in items:\n         if incomplete in value or incomplete in help:\n-            yield CompletionItem(value, help=help)\n+            out.append(CompletionItem(value, help=help))\n+\n+    return out\n \n \n @group.command(help=\"Choose a user\")\n", "issue": "Completion Example Error.\n<!--\r\nThis issue tracker is a tool to address bugs in Click itself. Please use\r\nPallets Discord or Stack Overflow for questions about your own code.\r\n\r\nReplace this comment with a clear outline of what the bug is.\r\n-->\r\n\r\n<!--\r\nDescribe how to replicate the bug.\r\n\r\nInclude a minimal reproducible example that demonstrates the bug.\r\nInclude the full traceback if there was an exception.\r\n-->\r\n\r\nWhen running completion example, try to do completion with completion `group select-user` and it will produce the following error.\r\n\r\n```\r\ncompletion group select-user bTraceback (most recent call last):      \r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/bin/completion\", line 11, in <module>\r\n    load_entry_point('click-example-completion', 'console_scripts', 'completion')()\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py\", line 1137, in __call__\r\n    return self.main(*args, **kwargs)\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py\", line 1057, in main\r\n    self._main_shell_completion(extra, prog_name, complete_var)\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py\", line 1132, in _main_shell_completion\r\n    rv = shell_complete(self, ctx_args, prog_name, complete_var, instruction)\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py\", line 49, in shell_complete\r\n    echo(comp.complete())\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py\", line 291, in complete\r\n    completions = self.get_completions(args, incomplete)\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/shell_completion.py\", line 273, in get_completions\r\n    return obj.shell_complete(ctx, incomplete)\r\n  File \"/Users/thomas/.pyenv/versions/3.8.5/lib/python3.8/site-packages/click/core.py\", line 2403, in shell_complete\r\n    if results and isinstance(results[0], str):\r\nTypeError: 'generator' object is not subscriptable\r\n```\r\n\r\n<!--\r\nDescribe the expected behavior that should have happened but didn't.\r\n-->\r\n\r\nEnvironment:\r\n\r\n- Python version:\r\n- Click version:\r\n\n", "before_files": [{"content": "import os\n\nimport click\nfrom click.shell_completion import CompletionItem\n\n\n@click.group()\ndef cli():\n    pass\n\n\n@cli.command()\n@click.option(\"--dir\", type=click.Path(file_okay=False))\ndef ls(dir):\n    click.echo(\"\\n\".join(os.listdir(dir)))\n\n\ndef get_env_vars(ctx, param, incomplete):\n    # Returning a list of values is a shortcut to returning a list of\n    # CompletionItem(value).\n    return [k for k in os.environ if incomplete in k]\n\n\n@cli.command(help=\"A command to print environment variables\")\n@click.argument(\"envvar\", shell_complete=get_env_vars)\ndef show_env(envvar):\n    click.echo(f\"Environment variable: {envvar}\")\n    click.echo(f\"Value: {os.environ[envvar]}\")\n\n\n@cli.group(help=\"A group that holds a subcommand\")\ndef group():\n    pass\n\n\ndef list_users(ctx, param, incomplete):\n    # You can generate completions with help strings by returning a list\n    # of CompletionItem. You can match on whatever you want, including\n    # the help.\n    items = [(\"bob\", \"butcher\"), (\"alice\", \"baker\"), (\"jerry\", \"candlestick maker\")]\n\n    for value, help in items:\n        if incomplete in value or incomplete in help:\n            yield CompletionItem(value, help=help)\n\n\n@group.command(help=\"Choose a user\")\n@click.argument(\"user\", shell_complete=list_users)\ndef select_user(user):\n    click.echo(f\"Chosen user is {user}\")\n\n\ncli.add_command(group)\n", "path": "examples/completion/completion.py"}], "after_files": [{"content": "import os\n\nimport click\nfrom click.shell_completion import CompletionItem\n\n\n@click.group()\ndef cli():\n    pass\n\n\n@cli.command()\n@click.option(\"--dir\", type=click.Path(file_okay=False))\ndef ls(dir):\n    click.echo(\"\\n\".join(os.listdir(dir)))\n\n\ndef get_env_vars(ctx, param, incomplete):\n    # Returning a list of values is a shortcut to returning a list of\n    # CompletionItem(value).\n    return [k for k in os.environ if incomplete in k]\n\n\n@cli.command(help=\"A command to print environment variables\")\n@click.argument(\"envvar\", shell_complete=get_env_vars)\ndef show_env(envvar):\n    click.echo(f\"Environment variable: {envvar}\")\n    click.echo(f\"Value: {os.environ[envvar]}\")\n\n\n@cli.group(help=\"A group that holds a subcommand\")\ndef group():\n    pass\n\n\ndef list_users(ctx, param, incomplete):\n    # You can generate completions with help strings by returning a list\n    # of CompletionItem. You can match on whatever you want, including\n    # the help.\n    items = [(\"bob\", \"butcher\"), (\"alice\", \"baker\"), (\"jerry\", \"candlestick maker\")]\n    out = []\n\n    for value, help in items:\n        if incomplete in value or incomplete in help:\n            out.append(CompletionItem(value, help=help))\n\n    return out\n\n\n@group.command(help=\"Choose a user\")\n@click.argument(\"user\", shell_complete=list_users)\ndef select_user(user):\n    click.echo(f\"Chosen user is {user}\")\n\n\ncli.add_command(group)\n", "path": "examples/completion/completion.py"}]}