Enum.split
You're seeing just the function
split, go back to Enum module for more information.
Specs
Splits the enumerable into two enumerables, leaving count
elements in the first one.
If count is a negative number, it starts counting from the
back to the beginning of the enumerable.
Be aware that a negative count implies the enumerable
will be enumerated twice: once to calculate the position, and
a second time to do the actual splitting.
Examples
iex> Enum.split([1, 2, 3], 2)
{[1, 2], [3]}
iex> Enum.split([1, 2, 3], 10)
{[1, 2, 3], []}
iex> Enum.split([1, 2, 3], 0)
{[], [1, 2, 3]}
iex> Enum.split([1, 2, 3], -1)
{[1, 2], [3]}
iex> Enum.split([1, 2, 3], -5)
{[], [1, 2, 3]}