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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def create_features(bam_in, loci_file, reference, out_dir):
 """ Use feature extraction module from CoRaL """

    lenvec_plus = op.join(out_dir, 'genomic_lenvec.plus')
    lenvec_minus = op.join(out_dir, 'genomic_lenvec.minus')
    compute_genomic_cmd = ("compute_genomic_lenvectors "
                           "{bam_in} {lenvec_plus} "
                           "{lenvec_minus} "
                           "{min_len} "
                           "{max_len} ")
    index_genomic_cmd = ("index_genomic_lenvectors "
                         "{lenvec} ")
    genomic_lenvec = op.join(out_dir, 'genomic_lenvec')
    feat_len_file = op.join(out_dir, 'feat_lengths.txt')
    compute_locus_cmd = ("compute_locus_lenvectors "
                         "{loci_file} "
                         "{genomic_lenvec} "
                         "{min_len} "
                         "{max_len} "
                         "> {feat_len_file}")
    cov_S_file = op.join(out_dir, 'loci.cov_anti')
    coverage_anti_cmd = ("coverageBed -S -counts -b "
                         "{bam_in} -a {loci_file} "
                         "> {cov_S_file}")
    feat_posentropy = op.join(out_dir, 'feat_posentropy.txt')
    entropy_cmd = ("compute_locus_entropy.rb "
                   "{counts_reads} "
                   "> {feat_posentropy}")
    with utils.chdir(out_dir):
        run(compute_genomic_cmd.format(min_len=min_trimmed_read_len, max_len=max_trimmed_read_len, **locals()), "Run compute_genomic")
        run(index_genomic_cmd.format(lenvec=lenvec_plus), "Run index in plus")
        run(index_genomic_cmd.format(lenvec=lenvec_minus), "Run index in minus")
        run(compute_locus_cmd.format(min_len=min_trimmed_read_len, max_len=max_trimmed_read_len, **locals()), "Run compute locus")
        run(coverage_anti_cmd.format(**locals()), "Run coverage antisense")
        feat_antisense = _order_antisense_column(cov_S_file, min_trimmed_read_len)

        counts_reads = _reads_per_position(bam_in, loci_file, out_dir)
        run(entropy_cmd.format(**locals()), "Run entropy")

        rnafold = calculate_structure(loci_file, reference)