public final CharSequence borrowSliceFrom(int start) {
        return CharBuffer.wrap(input, start, position);
    }
Gets a zero-copy slice of the expression starting from the given 0-based character position, read all the
way through to the current position of the parser.

@param start Position to slice from, ending at the current position.
@return Returns the zero-copy slice of the expression from {@code start} to {@link #position}.
smithy-utils/src/main/java/software/amazon/smithy/utils/SimpleParser.java