Change function call to symbol

Author: mroeschke

pandas/_libs/src/inference.pyx

@@ -1309,7 +1309,7 @@ def maybe_convert_objects(ndarray[object] objects, bint try_float=0,
 
     # we try to coerce datetime w/tz but must all have the same tz
     if seen.datetimetz_:
-        if len(set(getattr(val, 'tzinfo', None) for val in objects)) == 1:
+        if len({getattr(val, 'tzinfo', None) for val in objects}) == 1:
             from pandas import DatetimeIndex
             return DatetimeIndex(objects)
         seen.object_ = 1

pandas/_libs/tslibs/resolution.pyx

@@ -218,7 +218,7 @@ class Resolution(object):
         'U': 'N',
         'N': None}
 
-    _str_reso_map = dict((v, k) for k, v in _reso_str_map.items())
+    _str_reso_map = {v: k for k, v in _reso_str_map.items()}
 
     _reso_freq_map = {
         'year': 'A',
@@ -232,7 +232,7 @@ class Resolution(object):
         'microsecond': 'U',
         'nanosecond': 'N'}
 
-    _freq_reso_map = dict((v, k) for k, v in _reso_freq_map.items())
+    _freq_reso_map = {v: k for k, v in _reso_freq_map.items()}
 
     @classmethod
     def get_str(cls, reso):