Read a byte from the file without advancing to the next one. That is, successive calls to
peek() will return the same value, as will the next call to
This function is part of the Stream class, and can be called by any class that inherits from it (Wire, Serial, etc). See the Stream class main page for more information.
stream: an instance of a class that inherits from Stream.
The next byte (or character), or -1 if none is available.