'Create a HBFile instance.
Parameters
file : file-object
StringIO work as well
hb_info : HBInfo, optional
Should be given as an argument for writing, in which case the file
should be writable.'

def __init__(self, file, hb_info=None):

    self._fid = file
    if (hb_info is None):
        self._hb_info = HBInfo.from_file(file)
    else:
        self._hb_info = hb_info
