docstr: ...Test HawkesKernelSumExp string in list representation
          
code: def test_HawkesKernelSumExp_repr(self):
      """...Test HawkesKernelSumExp string in list representation"""
      self.assertEqual(
          str([self.hawkes_kernel_sumexp]),
          "[0.3*1*exp(-1*t) + 4*2*exp(-2*t) + " "2*0.2*exp(-0.2*t)]",
      )
  
file_path: tick/tick/hawkes/simulation/tests/hawkes_kernel_sum_exp_test.py
imports: import unittest
  import numpy
  from tick.hawkes import HawkesKernelSumExp
label_desc: Use image node_id 6 for calling the Test obj's underlying member method code with example usage: obj.test_HawkesKernelSumExp_repr() without return types