code: def _read_fasta_files(f, args):
      
      seq_l = {}
      sample_l = []
      idx = 1
      for line1 in f:
          line1 = line1.strip()
          cols = line1.split("\t")
          with open(cols[0], 'r') as fasta:
              sample_l.append(cols[1])
              for line in fasta:
                  if line.startswith(">"):
                      idx += 1
                      counts = int(re.search("x([0-9]+)", line.strip()).group(1))
                  else:
                      seq = line.strip()
                      seq = seq[0:int(args.maxl)] if len(seq) > int(args.maxl) else seq
                      if counts > int(args.minc) and len(seq) > int(args.minl):
                          if seq not in seq_l:
                              seq_l[seq] = sequence_unique(idx, seq)
                          seq_l[seq].add_exp(cols[1], counts)
      return seq_l, sample_l
docs: read fasta files of each sample and generate a seq_obj
      with the information of each unique sequence in each sample
  
      :param f: file containing the path for each fasta file and
      the name of the sample. Two column format with `tab` as field
      separator
  
      :returns: * :code:`seq_l`: is a list of seq_obj objects, containing
                 the information of each sequence
               * :code:`sample_l`: is a list with the name of the samples
                 (column two of the config file)