code: def test_direction():
      x, y, U, V = swirl_velocity_field()
      plt.streamplot(
          x,
          y,
          U,
          V,
          integration_direction="backward",
          maxlength=1.5,
          start_points=[[1.5, 0.0]],
          linewidth=2,
          density=2,
      )
  
file_path: matplotlib/lib/matplotlib/tests/test_streamplot.py
imports: import numpy
  from numpy.testing import assert_array_almost_equal
  import pytest
  import matplotlib.pyplot
  from matplotlib.testing.decorators import image_comparison
  import matplotlib.transforms
label_desc: Use image node_id 9 for calling a global function with example usage: test_direction() without return types