code: def test_solve_lin_sys_3x4_none():
      domain, x1, x2, x3, x4 = ring("x1,x2,x3,x4", QQ)
      eqs = [
          2 * x1 + x2 + 7 * x3 - 7 * x4 - 2,
          -3 * x1 + 4 * x2 - 5 * x3 - 6 * x4 - 3,
          x1 + x2 + 4 * x3 - 5 * x4 - 2,
      ]
      assert solve_lin_sys(eqs, domain) is None
  
file_path: sympy/sympy/polys/tests/test_solvers.py
imports: from sympy.matrices import Matrix
  from sympy.polys.domains import ZZ, QQ
  from sympy.polys.fields import field
  from sympy.polys.rings import ring
  from sympy.polys.solvers import solve_lin_sys, eqs_to_matrix
label_desc: Use image node_id 5 for calling a global function with example usage: test_solve_lin_sys_3x4_none() without return types