Specs

find_index(set :: t(), item :: Discord.SortedSet.Types.supported_term()) ::
  non_neg_integer() | nil | Discord.SortedSet.Types.common_errors()

Finds the index of the specified term.

Since SortedSet does enforce uniqueness of terms there is no need to worry about which index gets returned, the term either exists in the set or does not exist in the set. If the term exists the index of the term is returned, if not then nil is returned.