\section{\module{whichdb} ---         Guess which DBM module created a database} \declaremodule{standard}{whichdb}\modulesynopsis{Guess which DBM-style module created a given database.}  The single function in this module attempts to guess which of theseveral simple database modules available--\refmodule{dbm},\refmodule{gdbm}, or \refmodule{dbhash}--should be used to open agiven file. \begin{funcdesc}{whichdb}{filename}Returns one of the following values: \code{None} if the file can't beopened because it's unreadable or doesn't exist; the empty string(\code{''}) if the file's format can't be guessed; or a stringcontaining the required module name, such as \code{'dbm'} or\code{'gdbm'}.\end{funcdesc}