<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def getExpressionLevels( self, threshold=0.0, names=[], startIndex=0, maxResults=0):
 """ Returns the list of ExpressionLevels in this RNA Quantification. """

        rnaQuantificationId = self.getLocalId()
        with self._db as dataSource:
            expressionsReturned = dataSource.searchExpressionLevelsInDb(
                rnaQuantificationId,
                names=names,
                threshold=threshold,
                startIndex=startIndex,
                maxResults=maxResults)
            expressionLevels = [
                SqliteExpressionLevel(self, expressionEntry) for
                expressionEntry in expressionsReturned]
            return expressionLevels