code: def test_formula_params():
      t = F.Term("t")
      x, y = (sympy.Symbol(l) for l in "xy")
      f = F.Formula([t * x, y])
      assert set(f.params) == set([x, y] + list(f.coefs.values()))
  
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 3 for calling a global function with example usage: test_formula_params() without return types