code: def get_quantcols(pattern, oldheader, coltype):
      
      if pattern is None:
         return False
      if coltype == 'precur':
          return reader.get_cols_in_file(pattern, oldheader, single_col=True)
docs: Searches for quantification columns using pattern and header list.
      Calls reader function to do regexp. Returns a single column for
      precursor quant.