convert_dtype: eliminate "is True" and "is False".

Writing "if X is True" is almost always a mistake.

This change allows rdrecord to be called with "physical=1"
("physical=0" would work previously, but "physical=1" wouldn't) or
with "smooth_frames=0" ("smooth_frames=1" would work previously, but
"smooth_frames=0" wouldn't.)

Author: Benjamin Moody

wfdb/io/_signal.py

@@ -698,9 +698,9 @@ def convert_dtype(self, physical, return_res, smooth_frames):
         N/A
 
         """
-        if physical is True:
+        if physical:
             return_dtype = 'float'+str(return_res)
-            if smooth_frames is True:
+            if smooth_frames:
                 current_dtype = self.p_signal.dtype
                 if current_dtype != return_dtype:
                     self.p_signal = self.p_signal.astype(return_dtype, copy=False)
@@ -715,7 +715,7 @@ def convert_dtype(self, physical, return_res, smooth_frames):
                             self.p_signal[ch] = self.p_signal[ch].astype(return_dtype, copy=False)
         else:
             return_dtype = 'int'+str(return_res)
-            if smooth_frames is True:
+            if smooth_frames:
                 current_dtype = self.d_signal.dtype
                 if current_dtype != return_dtype:
                     # Do not allow changing integer dtype to lower value due to over/underflow