code: def repulsion_integral(
      basis_a, basis_b, basis_c, basis_d, normalize=True
  ):
      r"""Return a function that computes the electron-electron repulsion integral for four contracted
      Gaussian functions.
  
      Args:
          basis_a (~qchem.basis_set.BasisFunction): first basis function
          basis_b (~qchem.basis_set.BasisFunction): second basis function
          basis_c (~qchem.basis_set.BasisFunction): third basis function
          basis_d (~qchem.basis_set.BasisFunction): fourth basis function
          normalize (bool): if True, the basis functions get normalized
  
      Returns:
          function: function that computes the electron repulsion integral
  
      **Example**
  
      >>> symbols  = ['H', 'H']
      >>> geometry = np.array([[0.0, 0.0, 0.0], [0.0, 0.0, 1.0]], requires_grad = False)
      >>> alpha = np.array([[3.425250914, 0.6239137298, 0.168855404],
      >>>                   [3.425250914, 0.6239137298, 0.168855404],
      >>>                   [3.425250914, 0.6239137298, 0.168855404],
      >>>                   [3.425250914, 0.6239137298, 0.168855404]], requires_grad = True)
      >>> mol = qml.qchem.Molecule(symbols, geometry, alpha=alpha)
      >>> basis_a = mol.basis_set[0]
      >>> basis_b = mol.basis_set[1]
      >>> args = [mol.alpha]
      >>> repulsion_integral(basis_a, basis_b, basis_a, basis_b)(*args)
      0.45590152106593573
      """
  
      def _repulsion_integral(*args):
          r"""Compute the electron-electron repulsion integral for four contracted Gaussian functions.
  
          Args:
              *args (array[float]): initial values of the differentiable parameters
  
          Returns:
              array[float]: the electron repulsion integral between four contracted Gaussian functions
          """
          args_a = [arg[0] for arg in args]
          args_b = [arg[1] for arg in args]
          args_c = [arg[2] for arg in args]
          args_d = [arg[3] for arg in args]
  
          alpha, ca, ra = _generate_params(basis_a.params, args_a)
          beta, cb, rb = _generate_params(basis_b.params, args_b)
          gamma, cc, rc = _generate_params(basis_c.params, args_c)
          delta, cd, rd = _generate_params(basis_d.params, args_d)
  
          if basis_a.params[1].requires_grad or normalize:
              ca = ca * primitive_norm(basis_a.l, alpha)
              cb = cb * primitive_norm(basis_b.l, beta)
              cc = cc * primitive_norm(basis_c.l, gamma)
              cd = cd * primitive_norm(basis_d.l, delta)
  
              n1 = contracted_norm(basis_a.l, alpha, ca)
              n2 = contracted_norm(basis_b.l, beta, cb)
              n3 = contracted_norm(basis_c.l, gamma, cc)
              n4 = contracted_norm(basis_d.l, delta, cd)
          else:
              n1 = n2 = n3 = n4 = 1.0
  
          e = (
              n1
              * n2
              * n3
              * n4
              * (
                  (
                      ca
                      * cb[:, np.newaxis]
                      * cc[:, np.newaxis, np.newaxis]
                      * cd[:, np.newaxis, np.newaxis, np.newaxis]
                  )
                  * electron_repulsion(
                      basis_a.l,
                      basis_b.l,
                      basis_c.l,
                      basis_d.l,
                      ra,
                      rb,
                      rc,
                      rd,
                      alpha,
                      beta[:, np.newaxis],
                      gamma[:, np.newaxis, np.newaxis],
                      delta[:, np.newaxis, np.newaxis, np.newaxis],
                  )
              ).sum()
          )
          return e
  
      return _repulsion_integral
  
imports: import itertools
  import numpy
  from scipy.special import factorial2
  import pennylane
label_desc: Use image node_id 19 for calling a global function with example usage: repulsion_integral(basis_a, basis_b, basis_c, basis_d, normalize) and returns: _repulsion_integral, e