public final char peek(int offset) {
        int target = position + offset;
        if (target >= input.length() || target < 0) {
            return EOF;
        }

        return input.charAt(target);
    }
Returns the current character of the expression + {@code offset}
characters, but does not consume it.

<p>If the end of the expression is reached or if the peeked offset is
calculated to be less than 0, {@link Character#MIN_VALUE} is returned
(that is, '\0').

@param offset The number of characters to peek ahead (positive or negative).
@return Returns the peeked character.
smithy-utils/src/main/java/software/amazon/smithy/utils/SimpleParser.java