code: def test_factor_getterm():
      fac = F.Factor("f", "ab")
      assert fac["f_a"] == fac.get_term("a")
      fac = F.Factor("f", [1, 2])
      assert fac["f_1"] == fac.get_term(1)
      fac = F.Factor("f", [1, 2])
      pytest.raises(ValueError, fac.get_term, "1")
      m = fac.main_effect
      assert set(m.terms) == {fac["f_1"] - fac["f_2"]}
  
imports: from warnings import catch_warnings, simplefilter
  import numpy
  import pytest
  import sympy
  from numpy.core.records import fromrecords
  from numpy.testing import assert_almost_equal, assert_array_equal
  from sympy.utilities.lambdify import implemented_function
  from nipy.utils import VisibleDeprecationWarning
  from ..None import formulae
  from ..formulae import Term, terms
label_desc: Use image node_id 20 for calling a global function with example usage: test_factor_getterm() without return types