2.2 Prerequisites
This document is very far from self-contained.
It assumes the following:
-  The reader knows the C programming language
at least well
enough to understand function prototypes and return values.
-  The reader
has read the documents for one of Libmarpa’s upper layers.
As of this writing, the only such layer is Marpa::R2orMarpa::R3,
in Perl.
-  The reader knows some parsing theory.
See Parsing theory preliminaries.