code: def mesher():
      """A Mesher instance with sphere function and delta=0.1"""
      return Mesher(func=sphere, delta=0.1)
  
file_path: pyswarms/tests/utils/plotters/conftest.py
imports: import os
  import matplotlib
  import numpy
  import pytest
  from pyswarms.single import GlobalBestPSO
  from pyswarms.utils.functions.single_obj import sphere
  from pyswarms.utils.plotters.formatters import Mesher
label_desc: Use image node_id 3 for calling a global function with example usage: mesher() and returns: Mesher