def read_fasta(fasta_file):
    """
    Retrieve a DNA or protein sequence data from a FASTA file.

    Arguments:
        fasta_file (string): path to FASTA file.
    Returns:
        (string): DNA or protein sequence found in `fasta_file`.
    """
    sequence = ''
    with open(fasta_file) as read_file:
        for line in read_file:
            if line[0] not in ['>', ';']:
                sequence += line.strip()
    return(sequence)