code: def test_viewer_clear(self):
      table = Table({"a": [1, 2, 3]})
      viewer = PerspectiveViewer()
      viewer.load(table)
      viewer.clear()
      assert viewer.table.size() == 0
      assert viewer.table.schema() == {"a": int}
  
imports: import numpy
  import pandas
  from perspective import PerspectiveViewer, Table
label_desc: Use image node_id 18 for calling the TestViewer obj's underlying member method code with example usage: obj.test_viewer_clear() without return types