code: def gaussian_overlap(la, lb, ra, rb, alpha, beta):
      r"""Compute overlap integral for two primitive Gaussian functions.
  
      The overlap integral between two Gaussian functions denoted by :math:`a` and :math:`b` can be
      computed as [`Helgaker (1995) p803 <https://www.worldscientific.com/doi/abs/10.1142/9789812832115_0001>`_]:
  
      .. math::
  
          S_{ab} = E^{ij} E^{kl} E^{mn} \left (\frac{\pi}{p}  \right )^{3/2},
  
      where :math:`E` is a coefficient that can be computed recursively, :math:`i-n` are the angular
      momentum quantum numbers corresponding to different Cartesian components and :math:`p` is
      computed from the exponents of the two Gaussian functions as :math:`p = \alpha + \beta`.
  
      Args:
          la (integer): angular momentum for the first Gaussian function
          lb (integer): angular momentum for the second Gaussian function
          ra (float): position vector of the first Gaussian function
          rb (float): position vector of the second Gaussian function
          alpha (array[float]): exponent of the first Gaussian function
          beta (array[float]): exponent of the second Gaussian function
  
      Returns:
          array[float]: overlap integral between primitive Gaussian functions
  
      **Example**
  
      >>> la, lb = (0, 0, 0), (0, 0, 0)
      >>> ra, rb = np.array([0., 0., 0.]), np.array([0., 0., 0.])
      >>> alpha = np.array([np.pi/2])
      >>> beta = np.array([np.pi/2])
      >>> o = gaussian_overlap(la, lb, ra, rb, alpha, beta)
      >>> o
      array([1.])
      """
      p = alpha + beta
      s = 1.0
      for i in range(3):
          s = (
              s
              * qml.math.sqrt(np.pi / p)
              * expansion(la[i], lb[i], ra[i], rb[i], alpha, beta, 0)
          )
      return s
  
imports: import itertools
  import numpy
  from scipy.special import factorial2
  import pennylane
label_desc: Use image node_id 6 for calling a global function with example usage: gaussian_overlap(la, lb, ra, rb, alpha, beta) and returns: s