new_contents: '''
  Created on Oct 13, 2016
  
  Copyright 2016, Institute for Systems Biology.
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
  http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  
  @author: michael
  '''
  import gzip
  import pandas as pd
  
  from bigquery_etl.extract.utils import convert_file_to_dataframe
  from bigquery_etl.transform.tools import cleanup_dataframe
  from gdc.etl import etl
  from util import flatten_map
  
  class Mirna_expression_quantification(etl.Etl):
      
      def __init__(self):
          '''
          Constructor
          '''
          '''
          Constructor
  
          columns in the GDC file:
          miRNA_ID	read_count	reads_per_million_miRNA_mapped	cross-mapped
           
          columns for the BQ table:
          sample_barcode
          miRNA_ID
          read_count
          reads_per_million_miRNA_mapped
          cross-mapped
          project_short_name
          program_name
          sample_type_code
          file_name
          file_id
          aliquot_barcode
          case_barcode
          case_gdc_id
          sample_gdc_id
          aliquot_gdc_id
  
          '''
          pass
  
subject: add the etl script for miRNA expression quantification