text: def plug_in(symbol_values):
      c = symbol_values['C']
      return {'G': 1 / 15 * (c[0][0] + c[1][1] + c[2][2]) - 1 / 15 * (c[0][1] + c[1][2] + c[2][0]) +
                   1 / 5 * (c[3][3] + c[4][4] + c[5][5])}
  
  
  DESCRIPTION = """
  Model calculating an upper bound for Shear Modulus based on the Voigt 
  calculation, derived from the full elastic tensor.
  """
  
  config = {
      "name": "voigt_shear_modulus",
      "connections": [
          {
              "inputs": [
                  "C"
              ],
              "outputs": [
                  "G"
              ]
          }
      ],
      "categories": [
          "mechanical"
      ],
      "symbol_property_map": {
          "C": "elastic_tensor_voigt",
          "G": "shear_modulus"
      },
      "description": DESCRIPTION,
      "references": [],
      "implemented_by": [
          "dmrdjenovich"
      ],
      "plug_in": plug_in
  }
  