docstr: ...Test HawkesExpKern setting of parameter of C
          
docstr_tok: ["...","Test","HawkesExpKern","setting","of","parameter","of","C"]
code: def test_HawkesExpKern_penalty_C(self):
      """...Test HawkesExpKern setting of parameter of C"""
  
      for penalty in penalties:
          if penalty != "none":
              learner = HawkesExpKern(
                  self.decays, penalty=penalty, C=self.float_1
              )
              self.assertEqual(learner.C, self.float_1)
              self.assertEqual(
                  learner._prox_obj.strength, 1.0 / self.float_1
              )
              learner.C = self.float_2
              self.assertEqual(learner.C, self.float_2)
              self.assertEqual(
                  learner._prox_obj.strength, 1.0 / self.float_2
              )
  
              msg = "^``C`` must be positive, got -1$"
              with self.assertRaisesRegex(ValueError, msg):
                  HawkesExpKern(self.decays, penalty=penalty, C=-1)
  
          else:
              learner = HawkesExpKern(self.decays, penalty=penalty)
              msg = '^You cannot set C for penalty "%s"$' % penalty
              with self.assertWarnsRegex(RuntimeWarning, msg):
                  learner.C = self.float_1
  
          msg = "^``C`` must be positive, got -2$"
          with self.assertRaisesRegex(ValueError, msg):
              learner.C = -2
  
imports: import unittest
  import numpy
  from tick.base.inference import InferenceTest
  from tick.hawkes import SimuHawkesExpKernels
  from tick.hawkes.inference import HawkesExpKern
  from tick.hawkes.model.model_hawkes_expkern_leastsq import ModelHawkesExpKernLeastSq
  from tick.hawkes.model.model_hawkes_expkern_loglik import ModelHawkesExpKernLogLik
  from tick.prox import ProxNuclear
  from tick.prox import ProxPositive, ProxL1, ProxL2Sq, ProxElasticNet
  from tick.solver import AGD, GD, BFGS, SGD, SVRG
label_desc: Use image node_id 10 for calling the Test obj's underlying member method code with example usage: obj.test_HawkesExpKern_penalty_C() without return types