Fix type

Author: mthrok

torchaudio/functional.py

@@ -50,7 +50,7 @@ def istft(
         win_length: Optional[int] = None,
         window: Optional[Tensor] = None,
         center: bool = True,
-        pad_mode: str = None,
+        pad_mode: Optional[str] = None,
         normalized: bool = False,
         onesided: bool = True,
         length: Optional[int] = None,
@@ -248,13 +248,12 @@ def griffinlim(
         tprev = rebuilt
 
         # Invert with our current estimate of the phases
-        inverse = torch.istft(
-            specgram * angles,
-            n_fft=n_fft,
-            hop_length=hop_length,
-            win_length=win_length,
-            window=window,
-            length=length).float()
+        inverse = istft(specgram * angles,
+                        n_fft=n_fft,
+                        hop_length=hop_length,
+                        win_length=win_length,
+                        window=window,
+                        length=length).float()
 
         # Rebuild the spectrogram
         rebuilt = torch.stft(inverse, n_fft, hop_length, win_length, window,
@@ -267,13 +266,12 @@ def griffinlim(
         angles = angles.div_(complex_norm(angles).add_(1e-16).unsqueeze(-1).expand_as(angles))
 
     # Return the final phase estimates
-    waveform = torch.istft(
-        specgram * angles,
-        n_fft=n_fft,
-        hop_length=hop_length,
-        win_length=win_length,
-        window=window,
-        length=length)
+    waveform = istft(specgram * angles,
+                     n_fft=n_fft,
+                     hop_length=hop_length,
+                     win_length=win_length,
+                     window=window,
+                     length=length)
 
     # unpack batch
     waveform = waveform.reshape(shape[:-2] + waveform.shape[-1:])