Enum.take_every
You're seeing just the function
take_every, go back to Enum module for more information.
Specs
take_every(t(), non_neg_integer()) :: list()
Returns a list of every nth element in the enumerable,
starting with the first element.
The first element is always included, unless nth is 0.
The second argument specifying every nth element must be a non-negative
integer.
Examples
iex> Enum.take_every(1..10, 2)
[1, 3, 5, 7, 9]
iex> Enum.take_every(1..10, 0)
[]
iex> Enum.take_every([1, 2, 3], 1)
[1, 2, 3]