code: def disperse_charges(hemi, iters, const=0.2):
      """Models electrostatic repulsion on the unit sphere
  
      Places charges on a sphere and simulates the repulsive forces felt by each
      one. Allows the charges to move for some number of iterations and returns
      their final location as well as the total potential of the system at each
      step.
  
      Parameters
      ----------
      hemi : HemiSphere
          Points on a unit sphere.
      iters : int
          Number of iterations to run.
      const : float
          Using a smaller const could provide a more accurate result, but will
          need more iterations to converge.
  
      Returns
      -------
      hemi : HemiSphere
          Distributed points on a unit sphere.
      potential : ndarray
          The electrostatic potential at each iteration. This can be useful to
          check if the repulsion converged to a minimum.
  
      Notes
      -----
      This function is meant to be used with diffusion imaging so antipodal
      symmetry is assumed. Therefore, each charge must not only be unique, but if
      there is a charge at +x, there cannot be a charge at -x. These are treated
      as the same location and because the distance between the two charges will
      be zero, the result will be unstable.
      """
      if not isinstance(hemi, HemiSphere):
          raise ValueError("expecting HemiSphere")
      charges = hemi.vertices
      forces, v = _get_forces(charges)
      force_mag = np.sqrt((forces * forces).sum())
      const = const / force_mag.max()
      potential = np.empty(iters)
      v_min = v
  
      for ii in range(iters):
          new_charges = charges + forces * const
          norms = np.sqrt((new_charges**2).sum(-1))
          new_charges /= norms[:, None]
          new_forces, v = _get_forces(new_charges)
          if v <= v_min:
              charges = new_charges
              forces = new_forces
              potential[ii] = v_min = v
          else:
              const /= 2.0
              potential[ii] = v_min
  
      return HemiSphere(xyz=charges), potential
  
imports: import numpy
  import warnings
  from scipy import optimize
  from dipy.core.geometry import cart2sphere, sphere2cart, vector_norm
  from dipy.core.onetime import auto_attr
  from dipy.reconst.recspeed import remove_similar_vertices
label_desc: Use image node_id 8 for calling a global function with example usage: disperse_charges(hemi, iters, const) and returns: HemiSphere,  potential