   Returns true if the given year is a leap year.
 
   A leap year is a year of a longer length than normal. The exact meaning
-  is up to the calendar. A calendar must return `false` if does not support
+  is up to the calendar. A calendar must return `false` if it does not support
   the concept of leap years.
   """
   @callback leap_year?(year) :: boolean

  Only supports converting date times which are in the ISO calendar,
  attempting to convert date times from other calendars will raise.

  WARNING: the ISO8601 does contain the time zone nor its abbreviation,
  which means information is lost when converting to such format. This
  is also why this module does not provide a `from_iso8601/1` function,
  as it is impossible to build a proper `DateTime` from only the

  @doc """
  Parses the extended "Local time" format described by ISO8601:2004.

  Raises if the format is invalid.

  ## Examples

