title: How do I annotate each subplot separately in Plotly (Python)
body: <p>I am trying to associate a separate annotation object with each subplot in Plotly (Python), how can this be done?</p>
  
  <p><strong>What I tried</strong></p>
  
  <p>I am setting up the plot like this:</p>
  
  <pre><code>from plotly import tools
  fig = tools.make_subplots(rows=2, cols=1)
  fig.append_trace(traces[0], 1, 1)
  fig.append_trace(traces[1], 2, 1)
  </code></pre>
  
  <p>where each trace is formed like this:</p>
  
  <pre><code>import plotly.graph_objs as go
  traces[0] = go.Scatter(
              x=[1,2,3,4],
              y=[4,4,2,1],
              mode='markers'
          )
  </code></pre>
  
  <p>I know I can access the xaxis of each subplot separately via:</p>
  
  <pre><code>fig['layout']['xaxis1'].update(title='hello1')
  fig['layout']['xaxis2'].update(title='hello2')
  </code></pre>
  
  <p>But how can I access the annotation of each subplot? I tried "annotations1" and "annotation1", with no luck. I also tried to access the layout of subplot 1 via "layout1" as in:</p>
  
  <pre><code>fig['layout1'][...].update(...)
  </code></pre>
  
  <p>This did not work either.</p>