Each method asserts and deasserts signal respectively. They are equivalent
to .value(1) and .value(0) but conceptually simpler (and may help to avoid
confusion with inverted signals, where "asserted" state means logical 0
output).
A signal is like a pin, but ca also be inverted (active low). As such, it
abstracts properties of various physical devices, like LEDs, buttons,
relays, buzzers, etc. To instantiate a Signal:
pin = machine.Pin(...)
signal = machine.Signal(pin, inverted=True)
signal has the same .value() and __call__() methods as a pin.