type hints and lint

examples/fdtd.py

@@ -89,7 +89,7 @@ def perturbed_l3(a: float, radius: float, **kwargs) -> Pattern:
     return pat
 
 
-def main():
+def main() -> None:
     dtype = numpy.float32
     max_t = 3600            # number of timesteps
 
@@ -97,7 +97,6 @@ def main():
     pml_thickness = 8       # (number of cells)
 
     wl = 1550               # Excitation wavelength and fwhm
-    dwl = 100
 
     # Device design parameters
     xy_size = numpy.array([10, 10])