code: def make_histogram():
      source = data.movies.url
      return (
          alt.Chart(source)
          .mark_bar()
          .encode(
              alt.X("IMDB_Rating:Q", bin=True),
              y="count()",
          )
      )
  
file_path: vegafusion/python/vegafusion/tests/test_save.py
imports: import altair
  from vega_datasets import data
  import vegafusion
  from io import StringIO, BytesIO
  import json
label_desc: Use image node_id 1 for calling a global function with example usage: make_histogram() and returns: alt