def read_sequences_from_fasta_string(fasta_string):
    """reads the sequences contained in a FASTA string"""
    lines = fasta_string.split('\n')
    sequences = []
    seqbuffer = ''
    seqname = None
    for line in lines:
        line = line.strip()
        if line.startswith('>'):
            if len(seqbuffer) > 0:
                sequences.append((seqname, seqbuffer))
                seqbuffer = ''
            seqname = line[1:]
        elif line and len(line) > 0:
            seqbuffer += line
    if len(seqbuffer) > 0:
        sequences.append((seqname, seqbuffer))
    return sequences
