DSL: Allow specifying a list of line items in Visible Alpha signals. For
each evaluation company, the line items will be tried in turn util a
line item with data is found or the list is exchausted. See the
DSL documentation for
further information.
Use dates from the FactSet Fundamentals data for historical periods in the
publication_date() signal, and dates from the FactSet Estimates data for
future dates only. This aligns publication_date() with
company_calendar(alignment='pd').