def howToMigrate(self, fromVersion, toVersion=None):
<EOL>if toVersion is not None:<EOL><INDENT>return self.migrations[fromVersion:toVersion:<NUM_LIT:1>]<EOL><DEDENT>else:<EOL><INDENT>return self.migrations[fromVersion::<NUM_LIT:1>]<EOL><DEDENT>
Given a starting version and an ending version
        returns filenames of all the migrations in that range, exclusive.

        e.g.: [fromVersion, toVersion)