code: def sum_exponential_kernel(t, intensities, decays):
      return sum(
          [
              alpha * beta * np.exp(-beta * t)
              for alpha, beta in zip(intensities, decays)
          ]
      )
  
file_path: tick/tick/hawkes/model/tests/model_hawkes_test_utils.py
imports: import numpy
  from scipy.integrate import quad
label_desc: Use image node_id 2 for calling a global function with example usage: sum_exponential_kernel(t, intensities, decays) and returns: sum