You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: errorsas.go
    path of file: ./repos/gccrs/libgo/go/golang.org/x/tools/go/analysis/passes/errorsas
    
    the code of the file until where you have to start completion: // Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The errorsas package defines an Analyzer that checks that the second argument to
// errors.As is a pointer to a type implementing error.
package errorsas

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/
    
func run(pass *analysis.Pass) (interface{}, error) {
	switch pass.Pkg.Path() {
	case "errors", "errors_test":
		// These packages know how to use their own APIs.
		// Sometimes they are testing what happens to incorrect programs.
		return nil, nil
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		fn := typeutil.StaticCallee(pass.TypesInfo, call)
		if fn == nil {
			return // not a static call
		}
		if len(call.Args) < 2 {
			return // not enough arguments, e.g. called with return values of another function
		}
		if fn.FullName() == "errors.As" && !pointerToInterfaceOrError(pass, call.Args[1]) {
			pass.ReportRangef(call, "second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type")
		}
	})
	return nil, nil
}