code: def test_animate_hidden_function_type(pos_history):
      """Tests if the hidden _animate() function returns the expected type"""
      fig, ax = mpl.pyplot.subplots(1, 1)
      ax = mpl.pyplot.scatter(x=[], y=[])
      return_plot = _animate(i=1, data=pos_history, plot=ax)
      assert isinstance(return_plot, tuple)
  
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 7 for calling a global function with example usage: test_animate_hidden_function_type(pos_history) without return types