docstr: Read and return the HTML contents from a file_url
  in the form e.g. file:///Users/chriddyp/Repos/plotly.py/plotly-temp.html
docstr_tok: ["Read","and","return","the","HTML","contents","from","a","file_url","in","the","form","e.g",".","file",":","\/\/\/Users\/chriddyp\/Repos\/plotly.py\/plotly-temp.html"]
code: def _read_html(self, file_url):
      """Read and return the HTML contents from a file_url
      in the form e.g. file:///Users/chriddyp/Repos/plotly.py/plotly-temp.html
      """
      with open(file_url.replace("file://", "").replace(" ", "")) as f:
          return f.read()
  
imports: import json
  import os
  from unittest import TestCase
  import pytest
  import plotly
  import plotly.io
  from plotly.io._utils import plotly_cdn_url
label_desc: Use image node_id 3 for calling the PlotlyOfflineTestCase obj's underlying member method code with example usage: obj._read_html(file_url) and returns: f