+#include "xdiff/xdiff.h"
+
+/**
+ *
+ * Calling sequence:
+ * ----------------
+ *
+ * - Prepare a `struct ll_merge_options` to record options.
+ * If you have no special requests, skip this and pass `NULL`
+ * as the `opts` parameter to use the default options.
+ *
+ * - Allocate an mmbuffer_t variable for the result.
+ *
+ * - Allocate and fill variables with the file's original content
+ * and two modified versions (using `read_mmfile`, for example).
+ *
+ * - Call `ll_merge()`.
+ *
+ * - Read the merged content from `result_buf.ptr` and `result_buf.size`.
+ *
+ * - Release buffers when finished. A simple
+ * `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr);
+ * free(result_buf.ptr);` will do.
+ *
+ * If the modifications do not merge cleanly, `ll_merge` will return a
+ * nonzero value and `result_buf` will generally include a description of
+ * the conflict bracketed by markers such as the traditional `<<<<<<<`
+ * and `>>>>>>>`.
+ *
+ * The `ancestor_label`, `our_label`, and `their_label` parameters are
+ * used to label the different sides of a conflict if the merge driver
+ * supports this.
+ */
+
+
+struct index_state;
+
+/**
+ * This describes the set of options the calling program wants to affect
+ * the operation of a low-level (single file) merge.
+ */