prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Dots aren't showing up in ranged dot plot
  ![Screenshot from 2022-06-30 20-02-14](https://user-images.githubusercontent.com/9993/176815294-a1801b76-ed5a-4f3c-b38f-71850c131a5a.png)
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `altair/examples/ranged_dot_plot.py`
  Content:
  ```
  1 """
  2 Ranged Dot Plot
  3 -----------------
  4 This example shows a ranged dot plot that uses 'layer' to convey changing life expectancy for the five most populous countries (between 1955 and 2000).
  5 """
  6 # category: other charts
  7 import altair as alt
  8 from vega_datasets import data
  9 
  10 source = data.countries.url
  11 
  12 chart = alt.layer(
  13     data=source
  14 ).transform_filter(
  15     filter={"field": 'country',
  16             "oneOf": ["China", "India", "United States", "Indonesia", "Brazil"]}
  17 ).transform_filter(
  18     filter={'field': 'year',
  19             "oneOf": [1955, 2000]}
  20 )
  21 
  22 chart += alt.Chart().mark_line(color='#db646f').encode(
  23     x='life_expect:Q',
  24     y='country:N',
  25     detail='country:N'
  26 )
  27 # Add points for life expectancy in 1955 & 2000
  28 chart += alt.Chart().mark_point(
  29     size=100,
  30     opacity=1,
  31     filled=True
  32 ).encode(
  33     x='life_expect:Q',
  34     y='country:N',
  35     color=alt.Color('year:O',
  36         scale=alt.Scale(
  37             domain=['1955', '2000'],
  38             range=['#e6959c', '#911a24']
  39         )
  40     )
  41 ).interactive()
  42 
  43 chart
  44
  ```
  --- 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/altair/examples/ranged_dot_plot.py b/altair/examples/ranged_dot_plot.py
  --- a/altair/examples/ranged_dot_plot.py
  +++ b/altair/examples/ranged_dot_plot.py
  @@ -1,7 +1,7 @@
   """
   Ranged Dot Plot
  ------------------
  -This example shows a ranged dot plot that uses 'layer' to convey changing life expectancy for the five most populous countries (between 1955 and 2000).
  +---------------
  +This example shows a ranged dot plot to convey changing life expectancy for the five most populous countries (between 1955 and 2000).
   """
   # category: other charts
   import altair as alt
  @@ -9,7 +9,7 @@
   
   source = data.countries.url
   
  -chart = alt.layer(
  +chart = alt.Chart(
       data=source
   ).transform_filter(
       filter={"field": 'country',
  @@ -19,13 +19,13 @@
               "oneOf": [1955, 2000]}
   )
   
  -chart += alt.Chart().mark_line(color='#db646f').encode(
  +line = chart.mark_line(color='#db646f').encode(
       x='life_expect:Q',
       y='country:N',
       detail='country:N'
   )
   # Add points for life expectancy in 1955 & 2000
  -chart += alt.Chart().mark_point(
  +points = chart.mark_point(
       size=100,
       opacity=1,
       filled=True
  @@ -34,10 +34,10 @@
       y='country:N',
       color=alt.Color('year:O',
           scale=alt.Scale(
  -            domain=['1955', '2000'],
  +            domain=[1955, 2000],
               range=['#e6959c', '#911a24']
           )
       )
   ).interactive()
   
  -chart
  +(line + points)
  
verification_info: {"golden_diff": "diff --git a/altair/examples/ranged_dot_plot.py b/altair/examples/ranged_dot_plot.py\n--- a/altair/examples/ranged_dot_plot.py\n+++ b/altair/examples/ranged_dot_plot.py\n@@ -1,7 +1,7 @@\n \"\"\"\n Ranged Dot Plot\n------------------\n-This example shows a ranged dot plot that uses 'layer' to convey changing life expectancy for the five most populous countries (between 1955 and 2000).\n+---------------\n+This example shows a ranged dot plot to convey changing life expectancy for the five most populous countries (between 1955 and 2000).\n \"\"\"\n # category: other charts\n import altair as alt\n@@ -9,7 +9,7 @@\n \n source = data.countries.url\n \n-chart = alt.layer(\n+chart = alt.Chart(\n     data=source\n ).transform_filter(\n     filter={\"field\": 'country',\n@@ -19,13 +19,13 @@\n             \"oneOf\": [1955, 2000]}\n )\n \n-chart += alt.Chart().mark_line(color='#db646f').encode(\n+line = chart.mark_line(color='#db646f').encode(\n     x='life_expect:Q',\n     y='country:N',\n     detail='country:N'\n )\n # Add points for life expectancy in 1955 & 2000\n-chart += alt.Chart().mark_point(\n+points = chart.mark_point(\n     size=100,\n     opacity=1,\n     filled=True\n@@ -34,10 +34,10 @@\n     y='country:N',\n     color=alt.Color('year:O',\n         scale=alt.Scale(\n-            domain=['1955', '2000'],\n+            domain=[1955, 2000],\n             range=['#e6959c', '#911a24']\n         )\n     )\n ).interactive()\n \n-chart\n+(line + points)\n", "issue": "Dots aren't showing up in ranged dot plot\n![Screenshot from 2022-06-30 20-02-14](https://user-images.githubusercontent.com/9993/176815294-a1801b76-ed5a-4f3c-b38f-71850c131a5a.png)\r\n\n", "before_files": [{"content": "\"\"\"\nRanged Dot Plot\n-----------------\nThis example shows a ranged dot plot that uses 'layer' to convey changing life expectancy for the five most populous countries (between 1955 and 2000).\n\"\"\"\n# category: other charts\nimport altair as alt\nfrom vega_datasets import data\n\nsource = data.countries.url\n\nchart = alt.layer(\n    data=source\n).transform_filter(\n    filter={\"field\": 'country',\n            \"oneOf\": [\"China\", \"India\", \"United States\", \"Indonesia\", \"Brazil\"]}\n).transform_filter(\n    filter={'field': 'year',\n            \"oneOf\": [1955, 2000]}\n)\n\nchart += alt.Chart().mark_line(color='#db646f').encode(\n    x='life_expect:Q',\n    y='country:N',\n    detail='country:N'\n)\n# Add points for life expectancy in 1955 & 2000\nchart += alt.Chart().mark_point(\n    size=100,\n    opacity=1,\n    filled=True\n).encode(\n    x='life_expect:Q',\n    y='country:N',\n    color=alt.Color('year:O',\n        scale=alt.Scale(\n            domain=['1955', '2000'],\n            range=['#e6959c', '#911a24']\n        )\n    )\n).interactive()\n\nchart\n", "path": "altair/examples/ranged_dot_plot.py"}], "after_files": [{"content": "\"\"\"\nRanged Dot Plot\n---------------\nThis example shows a ranged dot plot to convey changing life expectancy for the five most populous countries (between 1955 and 2000).\n\"\"\"\n# category: other charts\nimport altair as alt\nfrom vega_datasets import data\n\nsource = data.countries.url\n\nchart = alt.Chart(\n    data=source\n).transform_filter(\n    filter={\"field\": 'country',\n            \"oneOf\": [\"China\", \"India\", \"United States\", \"Indonesia\", \"Brazil\"]}\n).transform_filter(\n    filter={'field': 'year',\n            \"oneOf\": [1955, 2000]}\n)\n\nline = chart.mark_line(color='#db646f').encode(\n    x='life_expect:Q',\n    y='country:N',\n    detail='country:N'\n)\n# Add points for life expectancy in 1955 & 2000\npoints = chart.mark_point(\n    size=100,\n    opacity=1,\n    filled=True\n).encode(\n    x='life_expect:Q',\n    y='country:N',\n    color=alt.Color('year:O',\n        scale=alt.Scale(\n            domain=[1955, 2000],\n            range=['#e6959c', '#911a24']\n        )\n    )\n).interactive()\n\n(line + points)\n", "path": "altair/examples/ranged_dot_plot.py"}]}