Availability:built-in
string(@Term)True if Term is bound to a string. Note that string here
refers to the built-in atomic type string as described in section
5.2. Starting with version 7, the syntax for a string object is
text between double quotes, such as "hello".66In
traditional Prolog systems, double quoted text is often mapped to a list
of character codes. See also the Prolog flag
double_quotes.