anchor.diff:        "is_valid_query": false,
         "tile_def": {
           "autoscale": true,
  -        "custom_unit": null,
           "text_align": "left",
           "precision": 2,
  +        "custom_unit": null,
           "viz": "query_value",
           "requests": [
             {
  
positive.code:       "is_valid_query": true,
        "tile_def": {
          "autoscale": true,
          "custom_unit": null,
          "text_align": "center",
          "precision": 2,
          "viz": "query_value",
          "requests": [
            {
  
negative.code:       "is_valid_query": false,
        "tile_def": {
          "autoscale": false,
          "text_align": "center",
          "precision": 0,
          "custom_unit": "%",
          "viz": "query_value",
          "requests": [
            {
  