List.keyfind

You're seeing just the function keyfind, go back to List module for more information.

keyfind(list, key, position, default \\ nil)

keyfind([tuple()], any(), non_neg_integer(), any()) :: any()

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key.

If no matching tuple is found, default is returned.

iex> List.keyfind([a: 1, b: 2], :a, 0)
{:a, 1}

iex> List.keyfind([a: 1, b: 2], 2, 1)
{:b, 2}

iex> List.keyfind([a: 1, b: 2], :c, 0)
nil