code: def volume_of_sphere(dim, radius):
      return (
          radius**dim
          * math.pi ** (0.5 * dim)
          / math.gamma(0.5 * dim + 1)
      )
  
file_path: pyro/pyro/distributions/testing/gof.py
imports: import math
  import warnings
  import torch
  from .special import chi2sf
label_desc: Use image node_id 6 for calling a global function with example usage: volume_of_sphere(dim, radius) and returns: unknown