code: def dipole_potential(x, y):
      """The electric dipole potential V, at position *x*, *y*."""
      r_sq = x**2 + y**2
      theta = np.arctan2(y, x)
      z = np.cos(theta) / r_sq
      return (np.max(z) - z) / (np.max(z) - np.min(z))
  
imports: import matplotlib.pyplot
  import numpy
  from matplotlib.tri import CubicTriInterpolator, Triangulation, UniformTriRefiner
label_desc: Use image node_id 1 for calling a global function with example usage: dipole_potential(x, y) and returns: unknown