import org.codehaus.groovy.ast.expr.ArgumentListExpression;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.ClosureExpression;
import org.codehaus.groovy.ast.expr.ConstantExpression;
import org.codehaus.groovy.ast.expr.ConstructorCallExpression;
import org.codehaus.groovy.ast.expr.DeclarationExpression;
import org.codehaus.groovy.ast.expr.ElvisOperatorExpression;

         "pluginVersion": "v11.0.0",
         "targets": [
            {
               "datasource": {
                  "type": "prometheus",
                  "uid": "$datasource"
               },
               "expr": "sum by (cluster, namespace, job) (\n    rate(\n        process_cpu_seconds_total{\n            cluster=~\"$cluster\",\n            namespace=~\"$namespace\",\n            job=~\"$job\"\n        }\n    [$__rate_interval])\n)\n",

func (check *Checker) singleIndex(expr *typeparams.IndexExpr) ast.Expr {
	if len(expr.Indices) == 0 {
		check.errorf(expr.Orig, InvalidSyntaxTree, "index expression %v with 0 indices", expr)
		return nil
	}
	if len(expr.Indices) > 1 {
		// TODO(rFindley) should this get a distinct error code?
		check.error(expr.Indices[1], InvalidIndex, invalidOp+"more than one index")
	}
	return expr.Indices[0]
}

                    FunctionArgument.Positional [indexes: 2..3, line/column: 1/3..1/4, file: test] (
                        expr = IntLiteral [indexes: 2..3, line/column: 1/3..1/4, file: test] (1)
                    )
                    FunctionArgument.Positional [indexes: 5..6, line/column: 1/6..1/7, file: test] (
                        expr = PropertyAccess [indexes: 5..6, line/column: 1/6..1/7, file: test] (
                            name = x

          },
          "expr": "go_memstats_heap_alloc_bytes{app=\"istiod\"}",
          "format": "time_series",
          "hide": true,
          "intervalFactor": 2,
          "legendFormat": "heap alloc",
          "refId": "D"
        },
        {
          "datasource": {
            "type": "prometheus",
            "uid": "${datasource}"
          },

	SliceExpr struct {
		X      Expr      // expression
		Lbrack token.Pos // position of "["
		Low    Expr      // begin of slice range; or nil
		High   Expr      // end of slice range; or nil
		Max    Expr      // maximum capacity of slice; or nil
		Slice3 bool      // true if 3-index slice (2 colons present)
		Rbrack token.Pos // position of "]"
	}

	// A TypeAssertExpr node represents an expression followed by a
	// type assertion.

			r := r.(*ir.TypeAssertExpr)
			r.X = o.expr(r.X, nil)
		case ir.ODYNAMICDOTTYPE2:
			r := r.(*ir.DynamicTypeAssertExpr)
			r.X = o.expr(r.X, nil)
			r.RType = o.expr(r.RType, nil)
			r.ITab = o.expr(r.ITab, nil)
		case ir.ORECV:
			r := r.(*ir.UnaryExpr)
			r.X = o.expr(r.X, nil)
		case ir.OINDEXMAP:
			r := r.(*ir.IndexExpr)
			r.X = o.expr(r.X, nil)
			r.Index = o.expr(r.Index, nil)

               },
               "expr": "sum by (pod) (\n  rate(\n    istio_tcp_connections_opened_total{pod=~\"ztunnel-.*\"}\n  [$__rate_interval])\n)",
               "legendFormat": "Opened ({{pod}})"
            },
            {
               "datasource": {
                  "type": "prometheus",
                  "uid": "$datasource"
               },

            "uid": "${datasource}"
          },
          "expr": "avg(envoy_wasm_envoy_wasm_runtime_null_active)",
          "interval": "",
          "legendFormat": "native",
          "refId": "A"
        },
        {
          "datasource": {
            "type": "prometheus",
            "uid": "${datasource}"
          },
          "expr": "avg(envoy_wasm_envoy_wasm_runtime_v8_active)",
          "interval": "",

			return
		}

		// rhs must be of the form: expr.(type) and expr must be an ordinary interface
		expr, _ := rhs.(*ast.TypeAssertExpr)
		if expr == nil || expr.Type != nil {
			check.error(s, InvalidSyntaxTree, "incorrect form of type switch guard")
			return
		}
		var x operand
		check.expr(nil, &x, expr.X)
		if x.mode == invalid {
			return
		}