def __str__(self):
    output = ''
    for (name, primer1, primer2) in self.primer_info:
        output += ('%s %s %s\n' % (name, primer1, primer2))
    return output
def __str__(self):
    output = 
    for (name, primer1, primer2) in self.primer_info:
        output += ('%s %s %s\n' % (name, primer1, primer2))
    return output