code: def generate_momentum_circle(d, massmatrix):
      """draw from a circle, with a little noise in amplitude"""
      momentum = np.random.multivariate_normal(
          np.zeros(d), np.dot(massmatrix, np.eye(d))
      )
      momentum *= (
          10 ** np.random.uniform(-0.3, 0.3)
          / (momentum**2).sum() ** 0.5
      )
      return momentum
  
imports: import numpy
  import matplotlib.pyplot
  import scipy.special
  import scipy.stats
label_desc: Use image node_id 9 for calling a global function with example usage: generate_momentum_circle(d, massmatrix) and returns: momentum