Function parse_bool_assignment_into 

pub fn parse_bool_assignment_into(
    lex: &mut Lexer<'_, AssignmentToken>,
    var_names: &mut VarNameManager,
    assignment: &mut Assignment<BooleanVar>,
) -> Result<(), Error>

Parse an assignment from a lexer into an existing Assignment of BooleanVar.

The assignment is formatted as a list of literals. A positive literal represents an assignment of the variable to true and a negative literal represents an assignment of the variable to false.

If a variable is already assigned in assignment, then it will be overwritten by the parsed assignment.