@classmethod
def parse_file_header(cls, file_head_bytes):
    """Parse a file header"""
    if not cls.header_type(file_head_bytes) is 'file':
        raise ValueError('Not a file header')
    file_head_desc = {}
    file_head_desc['block_type'] = 'file'
    major_version, minor_version = cls.data_version(file_head_bytes)
    file_head_desc['major_version'] = major_version
    file_head_desc['minor_version'] = minor_version
    return file_head_desc
