code: def mplot2d(f, var, *, show=True):
      """
      Plot a 2d function using matplotlib/Tk.
      """
  
      import warnings
  
      warnings.filterwarnings("ignore", r"Could not match \S")
  
      p = import_module("pylab")
      if not p:
          sys.exit("Matplotlib is required to use mplot2d.")
  
      if not is_sequence(f):
          f = [
              f,
          ]
  
      for f_i in f:
          x, y = sample(f_i, var)
          p.plot(x, y)
  
      p.draw()
      if show:
          p.show()
  
imports: import sys
  from sample import sample
  from sympy import sqrt, Symbol
  from sympy.utilities.iterables import is_sequence
  from sympy.external import import_module
label_desc: Use image node_id 1 for calling a global function with example usage: mplot2d(f, var) without return types