def _merge_to_base(source_df: pd.DataFrame, target_df: pd.DataFrame):
"""
"""
src_accs = list(source_df.Accession)
tgt_accs = list(target_df.Accession)
add_row_idxs: List[int] = []
for ii, src in enumerate(src_accs):
for jj, tgt in enumerate(tgt_accs):
if src & tgt:
tgt_accs[jj] = src | tgt
break
else:
add_row_idxs.append(ii)
target_df.Accession = tgt_accs
if add_row_idxs:
target_df = pd.concat([target_df, source_df.iloc[add_row_idxs]],
ignore_index=True)
return target_df
