$$ String ::= '"' {printing_char_except_double_quotes | '\"' | '\\'} '"' .
A string may consist of any number of characters (it may also be empty). It
must be enclosed in double quotes and must not extend over more than one line.
Within the double quotes there may be any combination of printable characters
except the backslash ``\
'' and the double quotes. These characters must
be preceded by a ``\
'' (escape character). Examples: "Hello", "He says: \
"Great\
"".