Create a list of the hints associated with this parameter assignment.
Generally there will be only one hint generated because we're currently
only displaying one hint at a time, ordering by distance from cursor
and severity. Since distance from cursor will be the same for all hints
from this assignment all but the most severe will ever be used. It might
make sense with more experience to alter this to function to be getHint()
function() {
        // Allow the parameter to provide documentation
        if (this.param.getCustomHint && this.value && this.arg) {
            var hint = this.param.getCustomHint(this.value, this.arg);
            if (hint) {
                return hint;
            }
        }

        // If there is no argument, use the cursor position
        var message = '<strong>' + this.param.name + '</strong>: ';
        if (this.param.description) {
            // TODO: This should be a short description - do we need to trim?
            message += this.param.description.trim();

            // Ensure the help text ends with '. '
            if (message.charAt(message.length - 1) !== '.') {
                message += '.';
            }
            if (message.charAt(message.length - 1) !== ' ') {
                message += ' ';
            }
        }
        var status = Status.VALID;
        var start = this.arg ? this.arg.start : Argument.AT_CURSOR;
        var end = this.arg ? this.arg.end : Argument.AT_CURSOR;
        var predictions;

        // Non-valid conversions will have useful information to pass on
        if (this.conversion) {
            status = this.conversion.status;
            if (this.conversion.message) {
                message += this.conversion.message;
            }
            predictions = this.conversion.predictions;
        }

        // Hint if the param is required, but not provided
        var argProvided = this.arg && this.arg.text !== '';
        var dataProvided = this.value !== undefined || argProvided;
        if (this.param.defaultValue === undefined && !dataProvided) {
            status = Status.INVALID;
            message += '<strong>Required<\strong>';
        }

        return new Hint(status, message, start, end, predictions);
    }