code: def test_type_C():
      c = CartanType("C4")
      m = Matrix(
          4, 4, [2, -1, 0, 0, -1, 2, -1, 0, 0, -1, 2, -1, 0, 0, -2, 2]
      )
      assert c.cartan_matrix() == m
      assert c.dimension() == 4
      assert c.simple_root(4) == [0, 0, 0, 2]
      assert c.roots() == 32
      assert c.basis() == 36
      assert c.lie_algebra() == "sp(8)"
      t = CartanType(["C", 3])
      assert t.dimension() == 3
      diag = "0---0---0=<=0\n1   2   3   4"
      assert c.dynkin_diagram() == diag
      assert c.positive_roots() == {
          1: [1, -1, 0, 0],
          2: [1, 1, 0, 0],
          3: [1, 0, -1, 0],
          4: [1, 0, 1, 0],
          5: [1, 0, 0, -1],
          6: [1, 0, 0, 1],
          7: [0, 1, -1, 0],
          8: [0, 1, 1, 0],
          9: [0, 1, 0, -1],
          10: [0, 1, 0, 1],
          11: [0, 0, 1, -1],
          12: [0, 0, 1, 1],
          13: [2, 0, 0, 0],
          14: [0, 2, 0, 0],
          15: [0, 0, 2, 0],
          16: [0, 0, 0, 2],
      }
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_type_C() without return types