code: def test_fit_chain(X):
      d = StudentT(3).fit(X[:4])
      _test_fit_params(
          d, [1.525, 1.375, 1.55], [0.931875, 0.626875, 0.5025]
      )
  
      d.fit(X[4:])
      _test_fit_params(
          d, [3.666667, 1.4, 1.466667], [1.742223, 0.14, 3.215556]
      )
  
      d = StudentT(3).fit(X)
      _test_fit_params(
          d,
          [2.442857, 1.385714, 1.514286],
          [2.402449, 0.418367, 1.666939],
      )
  
imports: import os
  import numpy
  import torch
  import pytest
  from pomegranate.distributions import StudentT
  from ._utils import _test_initialization_raises_two_parameters
  from ._utils import _test_initialization
  from ._utils import _test_predictions
  from ._utils import _test_efd_from_summaries
  from ._utils import _test_raises
  from nose.tools import assert_raises
  from numpy.testing import assert_array_almost_equal
label_desc: Use image node_id 36 for calling a global function with example usage: test_fit_chain(X) without return types