code: def test_len():
      assert not SparseMatrix()
      assert SparseMatrix() == SparseMatrix([])
      assert SparseMatrix() == SparseMatrix([[]])
  
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 9 for calling a global function with example usage: test_len() without return types