def read_fsas(ec_dir='/home/users/assafp/Database/EcoCyc/current/data'):
    """
    Read the fasta files of the chromosomes, return a dictionary from the
    chrname to the sequence
    Arguments:
    - `ec_dir`: main directory of EcoCyc
    """
    import glob
    from Bio import SeqIO
    fsa_seqs = {}
    for fsa_name in glob.glob('%s/*-*.fsa' % ec_dir):
        fsa_seqs[fsa_name.rsplit('.', 1)[0].split('-', 1)[1]] = SeqIO.read(open
            (fsa_name), 'fasta').seq
    return fsa_seqs
