new_contents: import numpy as np
  
  import vaex
  
  
  def test_dropinf():
      x = [1, 2, np.inf]
      y = [10, -np.inf, 2]
      z = [1, 2, 3]
  
      df = vaex.from_arrays(x=x, y=y, z=z)
      df_filter = df.dropinf()
  
      df_filter.shape == (1, 3)
      df_filter.values.tolist() == [[1.0, 10.0, 1.0]]
  
      df_filter = df.dropinf(column_names=['x'])
      df_filter.shape == (2, 3)
      df_filter.values.tolist() == [[1.0, 10.0, 1.0], [2.0, -np.inf, 2.0]]
  
subject: add dropinf tests