Define Extras module

I'll use as the host for utility functions needed to extend the stdlib.

1 files changed, 18 insertions, 0 deletions

diff --git a/assessments/semiprimes/server/lib/extras.ex b/assessments/semiprimes/server/lib/extras.ex
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+defmodule Extras do
+  @doc """
+  Return an ascending range starting at `a` and ending at `b` (exclusive).
+
+  ## Examples
+
+      iex> Extras.range(2, 5)
+      [2, 3, 4]
+
+  """
+  def range(a, b) do
+    if b <= a do
+      []
+    else
+      [a] ++ range(a + 1, b)
+    end
+  end
+end