new_contents: from __future__ import absolute_import, division, print_function
  
  import numpy as np
  import pandas as pd
  
  from .. import ggplot, aes, geom_point, geom_quantile
  from .conftest import cleanup
  
  n = 200  # Should not be too big, affects the test duration
  prng = np.random.RandomState(1234567890)
  # points that diverge like a point flash-light
  df = pd.DataFrame({'x': np.arange(n),
                     'y': np.arange(n) * (1 + prng.rand(n))
                     })
  
  
  @cleanup
  def test_lines():
      p = (ggplot(df, aes(x='x', y='y')) +
           geom_point(alpha=.5) +
           geom_quantile(quantiles=[.001, .5, .999], formula='y~x',
                         size=2))
  
      # Two (.001, .999) quantile lines should bound the points
      # from below and from above, and the .5 line should go
      # through middle (approximately).
      assert p == 'lines'
  
subject: Add geom_quantile tests