An instance of this class represents the initial fields that are
common to all standard forms line. Here is the class interface.
The status code must be a one-character string; see Section 6.21, “
# - - - - - c l a s s S t d H e a d class StdHead(object): '''Represents the front part of a standard forms line. Exports: StdHead ( hier, scan ): [ (hier is a Hier instance) and (scan is a Scan instance) -> if the line in scan starts with a standard forms head -> if the rank code is in hier -> scan := scan advanced past the head return a new StdHead instance representing the head else -> scan := scan not advanced past end of line raise KeyError else -> scan := scan advanced not past end of line Log() +:= error messages raise SyntaxError ] .rank: [ if the head had no rank code -> None else -> the rank as a Rank instance in hier ] .status: [ the status code as a string that matches STATUS_RE ] '''