Use pyupgrade to upgrade the code to use Python3 conventions (#138)

The pyupgrade project is available at
https://github.com/asottile/pyupgrade and can be installed through pip.

The pyupgrade tool automatically upgrades syntax for newer versions of
the language. As pyparsing is now Python 3 only, can apply some cleanups
and simplifications. Ran the tool using the following command:

    $ find . -name \*.py -exec pyupgrade --py3-plus {} \;

For now, pyparsing.py was skipped while it is refactored to a package.

1 files changed, 4 insertions, 4 deletions

diff --git a/examples/bigquery_view_parser.py b/examples/bigquery_view_parser.py
index f66155e..0277a17 100644
--- a/examples/bigquery_view_parser.py
+++ b/examples/bigquery_view_parser.py
@@ -26,10 +26,10 @@ class BigQueryViewParser:
         # Table names and alias names might differ by case, but that's not
         # relevant- aliases are not case sensitive
         lower_aliases = BigQueryViewParser.lowercase_set_of_tuples(with_aliases)
-        tables = set([
+        tables = {
             x for x in table_identifiers
             if not BigQueryViewParser.lowercase_of_tuple(x) in lower_aliases
-        ])
+        }
 
         # Table names ARE case sensitive as described at
         # https://cloud.google.com/bigquery/docs/reference/standard-sql/lexical#case_sensitivity
@@ -48,7 +48,7 @@ class BigQueryViewParser:
 
     @classmethod
     def lowercase_set_of_tuples(cls, set_of_tuples):
-        return set([BigQueryViewParser.lowercase_of_tuple(x) for x in set_of_tuples])
+        return {BigQueryViewParser.lowercase_of_tuple(x) for x in set_of_tuples}
 
     @classmethod
     def _get_parser(cls):
@@ -311,7 +311,7 @@ class BigQueryViewParser:
 
         case_when = WHEN + expr.copy()("when")
         case_then = THEN + expr.copy()("then")
-        case_clauses = Group(ZeroOrMore((case_when + case_then)))
+        case_clauses = Group(ZeroOrMore(case_when + case_then))
         case_else = ELSE + expr.copy()("else")
         case_stmt = (
             CASE