5432: ditch import statement in python

Obviously, the import statements cannot be put right before the methods in the same indentation.
It was there because there wasn't a better way to put these code.
Now, it is replaced with an worded instruction that imports are needed.

5432.tex

@@ -276,7 +276,9 @@ Voltages of all 4 channels are updated simultaneously with the use of \texttt{se
 A triangular waveform at 10 Hz, 16 V peak-to-peak.
 Timing accuracy of the RTIO system can be demonstrated by the precision of the frequency.
 
-\inputcolorboxminted{firstline=30,lastline=52}{examples/zotino.py}
+Import \texttt{scipy.signal} and \texttt{numpy} modules to run this example.
+
+\inputcolorboxminted{firstline=30,lastline=49}{examples/zotino.py}
 
 \section{Ordering Information}
 To order, please visit \url{https://m-labs.hk} and select the 5432 Zotino in the ARTIQ Sinara crate configuration tool. The card may also be ordered separately by writing to \url{mailto:sales@m-labs.hk}.

examples/zotino.py

@@ -27,9 +27,6 @@ class TriangularWave(EnvExperiment):
         self.setattr_device("core")
         self.zotino = self.get_device("zotino0")
 
-    from scipy import signal
-    import numpy
-
     def prepare(self):
         self.period = 0.1*s
         self.sample = 128