new_contents: """
  Scatter plots with a legend
  ---------------------------
  
  To create a scatter plot with a legend one may use a loop and create one scatter
  plot per item to appear in the legend and set the label accordingly.
  
  Modified from the matplotlib example:
  https://matplotlib.org/gallery/lines_bars_and_markers/scatter_with_legend.html
  """
  
  import numpy as np
  import pygmt
  
  np.random.seed(19680801)
  n = 200  # number of random data points
  
  fig = pygmt.Figure()
  fig.basemap(
      region=[-0.1, 1.1, -0.1, 1.1],
      projection="X10c/10c",
      frame=["xa0.2fg", "ya0.2fg", "WSrt"],
  )
  for color in ["blue", "orange", "green"]:
      x, y = np.random.rand(2, n)  # random X and Y data in [0,1]
      sizes = np.random.rand(n) * 0.5  # random size [0,0.5], in cm
      # plot data points as circles (style="c"), with different sizes
      fig.plot(
          x=x,
          y=y,
          style="c",
          sizes=sizes,
          color=color,
          # Set the legend label,
          # and set the circle size to be 0.25 cm (+S0.25c) in legend
          label=f"{color}+S0.25c",
          transparency=70,  # set transparency level for all symbols
      )
  
  fig.legend(transparency=30)  # set transparency level for legends
  fig.show()
  
subject: Add an example for scatter plots with auto legends (#607)