485: Highlights

You cannot add characters to a string or delete characters from a string.
If you want a read an entire line from a file stream, then instantiate the following pattern:
```
stream nextLine 
```
If you want to determine a stream is empty, then instantiate the following pattern:
```
stream atEnd 
```
If you want to determine whether a string is empty, then instantiate one of the following patterns:
```
string isEmpty 
string notEmpty 
```
If you want to extract a character from a string, then instantiate the following pattern:
```
string at: index 
```
If you want to read information from a string as though it were a stream, then instantiate the following pattern to produce a stream, and then read from the stream using, for example, nextWord.
```
string asStream 
```