code: def test_mesh_hidden_function_shape(mesher):
      """Tests if the hidden _mesh() function returns the expected shape"""
      xx, yy, zz = _mesh(mesher)
      assert xx.shape == yy.shape == zz.shape == (20, 20)
  
file_path: pyswarms/tests/utils/plotters/test_plotters.py
imports: import os
  import pytest
  import matplotlib
  from matplotlib.animation import FuncAnimation
  from matplotlib.axes import SubplotBase
  from pyswarms.utils.plotters import plot_contour, plot_cost_history, plot_surface
  from pyswarms.utils.plotters.plotters import _animate, _mesh
label_desc: Use image node_id 5 for calling a global function with example usage: test_mesh_hidden_function_shape(mesher) without return types