true when this token is the first non-whitespace token on its
line. Block-level rules (headings, lists, blockquotes) check this
flag before attempting to match.
Start/end location in the original source string
The lexeme category
The literal source text that produced this token
A single lexical token produced by the
Lexer.Tokens are the input to the parser stage. Each token carries its literal text (
value), source location (position), and a flag indicating whether it appeared at the beginning of a line — which matters because several Wikidot constructs (headings, lists, blockquotes, horizontal rules) are only valid at line start.