code: def test_hermitian():
      x = Symbol("x")
      a = SparseMatrix([[0, I], [-I, 0]])
      assert a.is_hermitian
      a = SparseMatrix([[1, I], [-I, 1]])
      assert a.is_hermitian
      a[0, 0] = 2 * I
      assert a.is_hermitian is False
      a[0, 0] = x
      assert a.is_hermitian is None
      a[0, 1] = a[1, 0] * I
      assert a.is_hermitian is False
  
imports: from sympy.core.numbers import Float, I, Rational
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol, symbols
  from sympy.functions.elementary.complexes import Abs
  from sympy.polys.polytools import PurePoly
  from sympy.matrices import Matrix, MutableSparseMatrix, ImmutableSparseMatrix, SparseMatrix, eye, ones, zeros, ShapeError, NonSquareMatrixError
  from sympy.testing.pytest import raises
label_desc: Use image node_id 16 for calling a global function with example usage: test_hermitian() without return types