+/**
+ * The graph API is used to draw a text-based representation of the commit
+ * history. The API generates the graph in a line-by-line fashion.
+ *
+ * Calling sequence
+ * ----------------
+ *
+ * - Create a `struct git_graph` by calling `graph_init()`. When using the
+ * revision walking API, this is done automatically by `setup_revisions()` if
+ * the '--graph' option is supplied.
+ *
+ * - Use the revision walking API to walk through a group of contiguous commits.
+ * The `get_revision()` function automatically calls `graph_update()` each time
+ * it is invoked.
+ *
+ * - For each commit, call `graph_next_line()` repeatedly, until
+ * `graph_is_commit_finished()` returns non-zero. Each call to
+ * `graph_next_line()` will output a single line of the graph. The resulting
+ * lines will not contain any newlines. `graph_next_line()` returns 1 if the
+ * resulting line contains the current commit, or 0 if this is merely a line
+ * needed to adjust the graph before or after the current commit. This return
+ * value can be used to determine where to print the commit summary information
+ * alongside the graph output.
+ *
+ * Limitations
+ * -----------
+ * - Check the graph_update() function for its limitations.
+ *
+ * - The graph API does not currently support reverse commit ordering. In
+ * order to implement reverse ordering, the graphing API needs an
+ * (efficient) mechanism to find the children of a commit.
+ *
+ * Sample usage
+ * ------------
+ *
+ * ------------
+ * struct commit *commit;
+ * struct git_graph *graph = graph_init(opts);
+ *
+ * while ((commit = get_revision(opts)) != NULL) {
+ * while (!graph_is_commit_finished(graph))
+ * {
+ * struct strbuf sb;
+ * int is_commit_line;
+ *
+ * strbuf_init(&sb, 0);
+ * is_commit_line = graph_next_line(graph, &sb);
+ * fputs(sb.buf, stdout);
+ *
+ * if (is_commit_line)
+ * log_tree_commit(opts, commit);
+ * else
+ * putchar(opts->diffopt.line_termination);
+ * }
+ * }
+ * ------------
+ * Sample output
+ * -------------
+ *
+ * The following is an example of the output from the graph API. This output does
+ * not include any commit summary information--callers are responsible for
+ * outputting that information, if desired.
+ * ------------
+ * *
+ * *
+ * *
+ * |\
+ * * |
+ * | | *
+ * | \ \
+ * | \ \
+ * *-. \ \
+ * |\ \ \ \
+ * | | * | |
+ * | | | | | *
+ * | | | | | *
+ * | | | | | *
+ * | | | | | |\
+ * | | | | | | *
+ * | * | | | | |
+ * | | | | | * \
+ * | | | | | |\ |
+ * | | | | * | | |
+ * | | | | * | | |
+ * * | | | | | | |
+ * | |/ / / / / /
+ * |/| / / / / /
+ * * | | | | | |
+ * |/ / / / / /
+ * * | | | | |
+ * | | | | | *
+ * | | | | |/
+ * | | | | *
+ * ------------
+ *
+ */
+