code: def ricker(points, a):
      """
      Return a Ricker wavelet, also known as the "Mexican hat wavelet".
  
      It models the function:
  
          ``A (1 - x^2/a^2) exp(-x^2/2 a^2)``,
  
      where ``A = 2/sqrt(3a)pi^1/4``.
  
      Parameters
      ----------
      points : int
          Number of points in `vector`.
          Will be centered around 0.
      a : scalar
          Width parameter of the wavelet.
  
      Returns
      -------
      vector : (N,) ndarray
          Array of length `points` in shape of ricker curve.
  
      Examples
      --------
      >>> import cupyx.scipy.signal
      >>> import cupy as cp
      >>> import matplotlib.pyplot as plt
  
      >>> points = 100
      >>> a = 4.0
      >>> vec2 = cupyx.scipy.signal.ricker(points, a)
      >>> print(len(vec2))
      100
      >>> plt.plot(cupy.asnumpy(vec2))
      >>> plt.show()
  
      """
      return _ricker_kernel(a, size=int(points))
  
imports: import cupy
  import numpy
  from cupyx.scipy.signal._signaltools import convolve
label_desc: Use image node_id 3 for calling a global function with example usage: ricker(points, a) and returns: _ricker_kernel