A.Enum.min_by

You're seeing just the function min_by, go back to A.Enum module for more information.
Link to this function

min_by(enumerable, fun, sorter \\ &<=/2, empty_fallback \\ fn -> raise(Enum.EmptyError) end)

View Source

Specs

min_by(
  t(val),
  (val -> key),
  (key, key -> boolean()) | module(),
  (() -> empty_result)
) :: val | empty_result
when val: value(), key: term(), empty_result: any()

Returns the minimal element in the enumerable as calculated by the given fun.

Mirrors Enum.min_by/4 with higher performance for Aja structures.