List.keyfind

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

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

View Source

Specs

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.

Examples

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