Reads data from the specified file number.
The file must first be opened in input-mode before this command can be used.
Reads occur at the position specified by the file pointer (see also Seek and FTell).
Data read from file will be placed into a variable.
Read statement overwrites the destination variable content with data content.
If the variable does not exist, it will be created.
Using a byte vector variable or a string the size may be any positive integer value.
Using plain type variable like integer or float the size must be equal to this variable size.
Example, how to print out a content of text file: