Get a file's MD5

def get_file_md5(filename):
    """Get a file's MD5"""
    if os.path.exists(filename):
        blocksize = 65536
        try:
            hasher = hashlib.md5()
        except BaseException:
            hasher = hashlib.new('md5', usedForSecurity=False)
        with open(filename, 'rb') as afile:
            buf = afile.read(blocksize)
            while len(buf) > 0:  # pylint: disable=len-as-condition
                hasher.update(buf)
                buf = afile.read(blocksize)
        return hasher.hexdigest()

    return ''