code: def test_beta_datatype(self):
      margin, nu, beta = 0.1, 0, 1
      loss_func = MarginLoss(margin=margin, nu=nu, beta=beta)
      self.assertTrue(len(loss_func.beta) == 1)
      loss_func = MarginLoss(
          margin=margin, nu=nu, beta=beta, learn_beta=True
      )
      self.assertTrue(len(loss_func.beta) == 1)
      loss_func = MarginLoss(
          margin=margin,
          nu=nu,
          beta=beta,
          learn_beta=True,
          num_classes=35,
      )
      self.assertTrue(len(loss_func.beta) == 35)
  
file_path: pytorch-metric-learning/tests/losses/test_margin_loss.py
imports: import unittest
  import torch
  from pytorch_metric_learning.losses import MarginLoss
  from ..None import TEST_DEVICE, TEST_DTYPES
  from ..zzz_testing_utils.testing_utils import angle_to_coord
  from .utils import get_triplet_embeddings_with_ref
label_desc: Use image node_id 5 for calling the TestMarginLoss obj's underlying member method code with example usage: obj.test_beta_datatype() without return types