old_contents: # -*- coding: utf-8 -*-
  """
  Test FastMarkerCluster
  ------------------
  """
  
  from jinja2 import Template
  import numpy as np
  
  import folium
  from folium import plugins
  
  
  def test_fast_marker_cluster():
      n = 100
      np.random.seed(seed=26082009)
      data = np.array([
          np.random.uniform(low=35, high=60, size=n),   # Random latitudes.
          np.random.uniform(low=-12, high=30, size=n),  # Random longitudes.
          range(n),                                     # Popups.
      ]).tolist()
      m = folium.Map([45., 3.], zoom_start=4)
      mc = plugins.FastMarkerCluster(data, callback=None)
      m.add_children(mc)
      m._repr_html_()
  
      out = m._parent.render()
  
      # We verify that imports
      assert ('<script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet.'
              'markercluster/0.4.0/leaflet.markercluster.js"></script>') in out
      assert ('<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/'
              'libs/leaflet.markercluster/0.4.0/MarkerCluster.css" />') in out
      assert ('<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/'
              'libs/leaflet.markercluster/0.4.0/MarkerCluster.Default.css" />'
              ) in out
  
      # Verify the script part is okay.
      tmpl = Template("""
          {% macro script(this, kwargs) %}
          (function() {
              var data = {{this._data}};
              var map = {{this._parent.get_name()}};
              var cluster = L.markerClusterGroup();
              {{this._callback}}
  
              for (var i = 0; i < data.length; i++) {
                  var row = data[i];
                  var marker = callback(row, popup='names');
                  marker.addTo(cluster);
              }
  
              cluster.addTo(map);
          })();
          {% endmacro %}
      """)
  
      assert ''.join(tmpl.render(this=mc).split()) in ''.join(out.split())
  
new_contents: # -*- coding: utf-8 -*-
  """
  Test FastMarkerCluster
  ------------------
  """
  
  from jinja2 import Template
  import numpy as np
  
  import folium
  from folium import plugins
  
  
  def test_fast_marker_cluster():
      n = 100
      np.random.seed(seed=26082009)
      data = np.array([
          np.random.uniform(low=35, high=60, size=n),   # Random latitudes.
          np.random.uniform(low=-12, high=30, size=n),  # Random longitudes.
          range(n),                                     # Popups.
      ]).tolist()
      m = folium.Map([45., 3.], zoom_start=4)
      mc = plugins.FastMarkerCluster(data, callback=None)
      m.add_child(mc)
      m._repr_html_()
  
      out = m._parent.render()
  
      # We verify that imports
      assert ('<script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet.'
              'markercluster/0.4.0/leaflet.markercluster.js"></script>') in out
      assert ('<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/'
              'libs/leaflet.markercluster/0.4.0/MarkerCluster.css" />') in out
      assert ('<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/'
              'libs/leaflet.markercluster/0.4.0/MarkerCluster.Default.css" />'
              ) in out
  
      # Verify the script part is okay.
      tmpl = Template("""
          {% macro script(this, kwargs) %}
          (function() {
              var data = {{this._data}};
              var map = {{this._parent.get_name()}};
              var cluster = L.markerClusterGroup();
              {{this._callback}}
  
              for (var i = 0; i < data.length; i++) {
                  var row = data[i];
                  var marker = callback(row, popup='names');
                  marker.addTo(cluster);
              }
  
              cluster.addTo(map);
          })();
          {% endmacro %}
      """)
  
      assert ''.join(tmpl.render(this=mc).split()) in ''.join(out.split())
  
subject: Remove deprecated add_children method call