Gathers data from streams into local CSV file, then creates a swarm 
    description for it. 
    :param predictedField: (string)
    :param swarmParams: (dict) overrides any swarm params

def prepareSwarm(self, predictedField=None, swarmParams=None):
    """
    Gathers data from streams into local CSV file, then creates a swarm 
    description for it. 
    :param predictedField: (string)
    :param swarmParams: (dict) overrides any swarm params
    """
    csvPath, workingDirPath = self.populateCsv()
    swarmDescriptionPath = os.path.join(
      workingDirPath, "swarm_description.json"
    )
    self.writeSwarmDescription(
      csvPath, swarmDescriptionPath, 
      predictedField=predictedField, swarmParams=swarmParams
    )