code: def test_linestyles(style):
      delta = 0.025
      x = np.arange(-3.0, 3.0, delta)
      y = np.arange(-2.0, 2.0, delta)
      X, Y = np.meshgrid(x, y)
      Z1 = np.exp(-(X**2) - Y**2)
      Z2 = np.exp(-((X - 1) ** 2) - (Y - 1) ** 2)
      Z = (Z1 - Z2) * 2
  
      # Positive contour defaults to solid
      fig1, ax1 = plt.subplots()
      CS1 = ax1.contour(X, Y, Z, 6, colors="k")
      ax1.clabel(CS1, fontsize=9, inline=True)
      ax1.set_title("Single color - positive contours solid (default)")
      assert CS1.linestyles is None  # default
  
      # Change linestyles using linestyles kwarg
      fig2, ax2 = plt.subplots()
      CS2 = ax2.contour(X, Y, Z, 6, colors="k", linestyles=style)
      ax2.clabel(CS2, fontsize=9, inline=True)
      ax2.set_title(f"Single color - positive contours {style}")
      assert CS2.linestyles == style
  
      # Ensure linestyles do not change when negative_linestyles is defined
      fig3, ax3 = plt.subplots()
      CS3 = ax3.contour(
          X,
          Y,
          Z,
          6,
          colors="k",
          linestyles=style,
          negative_linestyles="dashdot",
      )
      ax3.clabel(CS3, fontsize=9, inline=True)
      ax3.set_title(f"Single color - positive contours {style}")
      assert CS3.linestyles == style
  
imports: import datetime
  import platform
  import re
  from unittest import mock
  import contourpy
  import numpy
  from numpy.testing import assert_array_almost_equal, assert_array_almost_equal_nulp, assert_array_equal
  import matplotlib
  from matplotlib import pyplot, rc_context, ticker
  from matplotlib.colors import LogNorm, same_color
  import matplotlib.patches
  from matplotlib.testing.decorators import check_figures_equal, image_comparison
  import pytest
label_desc: Use image node_id 40 for calling a global function with example usage: test_linestyles(style) without return types