
  [;1m-spec abs(Float) -> float() when Float :: float();[0m
  [;1m         (Int) -> non_neg_integer() when Int :: integer().[0m

  Returns an integer or float that is the arithmetical absolute
  value of [;;4mFloat[0m or [;;4mInt[0m, for example:

    > abs(-3.33).
    3.33
    > abs(-3).
    3

  Allowed in guard tests.
