Enum.fetch-exclamation-mark

You're seeing just the function fetch-exclamation-mark, go back to Enum module for more information.

fetch!(enumerable, index)

fetch!(t(), index()) :: element()

Finds the element at the given index (zero-based).

Raises OutOfBoundsError if the given index is outside the range of the enumerable.

iex> Enum.fetch!([2, 4, 6], 0)
2

iex> Enum.fetch!([2, 4, 6], 2)
6

iex> Enum.fetch!([2, 4, 6], 4)
** (Enum.OutOfBoundsError) out of bounds error