code: def test_colormap():
      X, Y, U, V = velocity_field()
      plt.streamplot(
          X,
          Y,
          U,
          V,
          color=U,
          density=0.6,
          linewidth=2,
          cmap=plt.cm.autumn,
      )
      plt.colorbar()
  
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 4 for calling a global function with example usage: test_colormap() without return types