Kernel.SpecialForms.unquote_splicing

You're seeing just the macro unquote_splicing, go back to Kernel.SpecialForms module for more information.
Link to this macro

unquote_splicing(expr)

View Source (macro)

Unquotes the given list expanding its arguments.

Similar to unquote/1.

Examples

iex> values = [2, 3, 4]
iex> quote do
...>   sum(1, unquote_splicing(values), 5)
...> end
{:sum, [], [1, 2, 3, 4, 5]}