code: def test_solve_lin_sys_4x7_inf():
      domain, x1, x2, x3, x4, x5, x6, x7 = ring(
          "x1,x2,x3,x4,x5,x6,x7", QQ
      )
      eqs = [
          x1 + 4 * x2 - x4 + 7 * x6 - 9 * x7 - 3,
          2 * x1 + 8 * x2 - x3 + 3 * x4 + 9 * x5 - 13 * x6 + 7 * x7 - 9,
          2 * x3 - 3 * x4 - 4 * x5 + 12 * x6 - 8 * x7 - 1,
          -x1
          - 4 * x2
          + 2 * x3
          + 4 * x4
          + 8 * x5
          - 31 * x6
          + 37 * x7
          - 4,
      ]
      sol = {
          x1: 4 - 4 * x2 - 2 * x5 - x6 + 3 * x7,
          x3: 2 - x5 + 3 * x6 - 5 * x7,
          x4: 1 - 2 * x5 + 6 * x6 - 6 * x7,
      }
      assert solve_lin_sys(eqs, domain) == sol
  
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 6 for calling a global function with example usage: test_solve_lin_sys_4x7_inf() without return types