code review 5783092: os: remove document duplication in error predicate functions

src/pkg/os/error.go

 // Copyright 2009 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.
 
 package os
 
 import (
         "errors"
 )
 
@@ skipping 24 matching lines @@
 
 // NewSyscallError returns, as an error, a new SyscallError
 // with the given system call name and error details.
 // As a convenience, if err is nil, NewSyscallError returns nil.
 func NewSyscallError(syscall string, err error) error {
         if err == nil {
                 return nil
         }
         return &SyscallError{syscall, err}
 }
+
+// IsExist returns whether the error is known to report that a file already exists.
+// It is satisfied by ErrExist as well as some syscall errors.
+func IsExist(err error) bool {
+        return isExist(err)
+}
+
+// IsNotExist returns whether the error is known to report that a file does not exist.
+// It is satisfied by ErrNotExist as well as some syscall errors.
+func IsNotExist(err error) bool {
+        return isNotExist(err)
+}
+
+// IsPermission returns whether the error is known to report that permission is denied.
+// It is satisfied by ErrPermission as well as some syscall errors.
+func IsPermission(err error) bool {
+        return isPermission(err)
+}