docs: def parse_single_meta(self, fname, selected_meta_data):
          """
          Parses a single meta data file
          :param fname: name of the file
          :param selected_meta_data: If not none then only the specified columns of metadata are parsed
          :return: the resulting pandas series
          """
          # reads a meta data file into a dataframe
          columns = []
          data = []
          with open(fname) as f:
              for line in f:
                  splitted = line.split('\t')
                  columns.append(splitted[0])
                  data.append(splitted[1].split('\n')[0])  # to remove the \n values
          df = pd.DataFrame(data=data, index=columns)
          df = df.T
          sample = self._get_sample_name(fname)
          if selected_meta_data:  # if null then keep all the columns
              try:
                  df = df[selected_meta_data]
              except:
                  pass
          df['sample'] = sample
          return df