In this example, the problem is that the second line is indented by one space. But the error
message points to y, which is misleading. In general, error messages indicate where the
problem was discovered, but the actual error might be earlier in the code, sometimes on a
previous line.
The same is true of runtime errors. Suppose you are trying to compute a signal-to-noise
ratio in decibels. The formula is SNRdb = 10 log10(Psignal/Pnoise). In Python, you might
write something like this: