Just a warning, the following example is ignorant of i/k/a-rates, along with pass-by-reference vs pass-by-value:

import FX
import Master
import Mixer
from Envelope import line
from TestLibrary.Instruments import SineTone

# Create instances of objects and patch together
st = SineTone()                             # Simple sine instrument
reverb = FX.Reverb(input=st.out, time=3.1)  # Reverb unit
mix = Mixer.pan(0, st.out, reverb.out)      # Dry/wet: value, sig 1, sig 2
output = Master.DAC(mix)                    # Main output

# Score
@0 turnon(reverb, mix, output)  # Turn on selected instances

@0 st.play(20, 1, 440)        # Play for 20 seconds, amp = 1, frequency = 440
@0 st.amp *= line(0, 10, 1)   # Amplitude rise
@10 st.amp *= line(1, 10, 0)  # Amplitude fall
@20 mix.pan = line(1, 20, 0)  # Dry to wet over 20 seconds

@10 reverb.time += line(0, 5, 8.1)  # Increase reverb time starting at 10
@20:
    @reverb.time turnoff(reverb, mix, output)  # Turnoff selected instances

The import section loads classes from existing instrument/unit generator libraries.

In the orchestra, instances are created from the imported classes, and patched together into a simple instrument graph. There’s a simple sine instrument, which is plugged into a reverb unit. Next, there is the pan mixer, which has the dry sine instrument plugged into one side, and the wet reverb signal plugged into the other; It is initially set to 100% dry. The pan mixer is then patched into the output, which sends the audio to the DAC.

The first line in the score turns on three instruments: reverb, mix and output. There will be times when the duration is unknown. The ability to start and stop machines is a must.

The sine instrument starts with a duration of 20, an amplitude of 1 and a frequency of 440. The amplitude of the sine is modulated by two envelopes, creating a rise/fall shape. Line envelopes also modulate the dry/wet mixer and reverb time.

At the end, the turnoff function shuts down reverb, mix and output.

Bonus round: Why do you suppose I wrote,

@20:
    @reverb.time turnoff(reverb, mix, output)  # Turnoff selected instances

instead of this?

@(20 + reverb.time) turnoff(reverb, mix, output)  # Turnoff selected instances