code: def hello():
      # Generate the figure **without using pyplot**.
      fig = Figure()
      ax = fig.subplots()
      ax.plot([1, 2])
      # Save it to a temporary buffer.
      buf = BytesIO()
      fig.savefig(buf, format="png")
      # Embed the result in the html output.
      data = base64.b64encode(buf.getbuffer()).decode("ascii")
      return f"<img src='data:image/png;base64,{data}'/>"
  
imports: import base64
  from io import BytesIO
  from flask import Flask
  from matplotlib.figure import Figure
label_desc: Use image node_id 1 for calling a global function with example usage: hello() and returns: str, data, str