|A Posting represents a MixedAmount being added to or subtracted from a
single Account. Each Transaction contains two or more postings which
should add up to 0. Postings also reference their parent transaction, so
we can get a date or description for a posting (from the transaction).
|Does this posting fall within the given date span ?
|Get the minimal date span which contains all the postings, or
DateSpan Nothing Nothing if there are none.
|Produced by Haddock version 2.6.0|