character hexadecimal encoding of the hash of the object (possibly
followed by a white space).
-object type:
+object type::
One of the identifiers "commit","tree","tag" and "blob" describing
the type of an object.
A tag is most typically used to mark a particular point in the
commit ancestry chain.
-unmerged index:
+unmerged index::
An index which contains unmerged index entries.
working tree::