code: def mutect_to_bed(df):
      
      s = (df.contig.astype(str) + '\t' + 
           (df.position - 1).astype(int).astype(str) + '\t' + 
           df.position.astype(int).astype(str) + '\t' + 
           df.tumor_name)
      s = '\n'.join(s.values) + '\n'
      bt = pbt.BedTool(s, from_string=True)
      return bt
docs: Convert MuTect results (read into dataframe) to BedTool object
  
      Parameters
      ----------
      df : pandas.DataFrame
          Pandas DataFrame with MuTect results.
  
      Returns
      -------
      bt : pybedtools.BedTool
          BedTool with variants.