code: def _calc_arrow_width(strength: float, max_strength: float):
      if max_strength == 0:
          return 4.1
      elif max_strength < 0:
          raise ValueError(
              "Got a negative strength! The strength needs to be positive."
          )
  
      return 0.1 + 4.0 * float(abs(strength)) / float(max_strength)
  
file_path: dowhy/dowhy/utils/plotting.py
imports: import logging
  import os
  import tempfile
  from typing import Any, Dict, List, Optional, Tuple, Union
  import matplotlib.pyplot
  import networkx
  import numpy
  import pandas
  from matplotlib import image
label_desc: Use image node_id 4 for calling a global function with example usage: _calc_arrow_width(strength, max_strength) and returns: unknown, int