title: Plotly add_trace vs append_trace
body: <p>Is there any difference between <code>add_trace</code> and <code>append_trace</code> in Plotly? Is the latter a legacy of the former?</p>
  <p>In the <a href="https://github.com/plotly/plotly.py" rel="noreferrer">Plotly.py GitHub</a>, there are 88 markdown + 21 Python instances of <code>add_trace</code> and 9 markdowbn + 7 Python instances of <code>append_trace</code>. The latter are mainly coming from <code>doc</code> and <code>packages/python/plotly/plotly/figure_factory</code>.</p>
  <p>In the <a href="https://plotly.com/python/subplots/" rel="noreferrer">Plotly subplots documentation</a>, there are 4 instances of <code>append_trace</code> while all other 52 instances are <code>add_trace</code>.</p>
  <p>Here is an example extracted from there:</p>
  <pre><code>from plotly.subplots import make_subplots
  import plotly.graph_objects as go
  
  fig = make_subplots(rows=3, cols=1)
  
  fig.append_trace(go.Scatter(
      x=[3, 4, 5],
      y=[1000, 1100, 1200],
  ), row=1, col=1)
  
  fig.append_trace(go.Scatter(
      x=[2, 3, 4],
      y=[100, 110, 120],
  ), row=2, col=1)
  
  fig.append_trace(go.Scatter(
      x=[0, 1, 2],
      y=[10, 11, 12]
  ), row=3, col=1)
  
  
  fig.update_layout(height=600, width=600, title_text=&quot;Stacked Subplots&quot;)
  fig.show()
  </code></pre>
  <p>I have tried replacing the <code>append_trace</code> instances in this code snippets to <code>add_trace</code> and did not observe any apparent differences.</p>