Circuits.GPIO.Chip.set_values

You're seeing just the function set_values, go back to Circuits.GPIO.Chip module for more information.
Link to this function

set_values(line_handle, values)

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Specs

set_values(Circuits.GPIO.Chip.LineHandle.t(), [offset_value()]) ::
  :ok | {:error, atom()}

Set values of the GPIOs

{:ok, line_handle} = Circuits.GPIO.Chip.request_lines(my_gpio_chip, [17, 24, 22])
{:ok, [0, 0, 0]} = Circuits.GPIO.Chip.read_value(line_handle)
:ok = Circuits.GPIO.Chip.set_value(line_handle, [1, 0, 1])
{:ok, [1, 0, 1]} = Circuits.GPIO.Chip.read_value(line_handle)

Note that the order of the values that were sent matches the order by which the GPIO offsets where requested. In the example above offset 17 was set to 1, offset 24 was stayed at 0, offset 22 was set to 1.