Issue #11426: use 'with' statements on open files in CSV examples

Doc/library/csv.rst

@@ -442,36 +442,39 @@ Examples
 The simplest example of reading a CSV file::
 
    import csv
-   reader = csv.reader(open("some.csv", "rb"))
+   with open('some.csv', 'rb') as f:
+       reader = csv.reader(f)
        for row in reader:
            print row
 
 Reading a file with an alternate format::
 
    import csv
-   reader = csv.reader(open("passwd", "rb"), delimiter=':', quoting=csv.QUOTE_NONE)
+   with open('passwd', 'rb') as f:
+       reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE)
        for row in reader:
            print row
 
 The corresponding simplest possible writing example is::
 
    import csv
-   writer = csv.writer(open("some.csv", "wb"))
+   with open('some.csv', 'wb') as f:
+       writer = csv.writer(f)
        writer.writerows(someiterable)
 
 Registering a new dialect::
 
    import csv
-
    csv.register_dialect('unixpwd', delimiter=':', quoting=csv.QUOTE_NONE)
-
-   reader = csv.reader(open("passwd", "rb"), 'unixpwd')
+   with open('passwd', 'rb') as f:
+       reader = csv.reader(f, 'unixpwd')
 
 A slightly more advanced use of the reader --- catching and reporting errors::
 
    import csv, sys
-   filename = "some.csv"
-   reader = csv.reader(open(filename, "rb"))
+   filename = 'some.csv'
+   with open(filename, 'rb') as f:
+       reader = csv.reader(f)
        try:
            for row in reader:
                print row