Changes the value stored by a variable.
VARVALSET variable TO expression [THEN statement(s) | ELSE statement(s)]
variable A string containing the name of the variable whose value is to be changed.
expression An expression that evaluates to a numeric or string value.
The variable will not be updated if it does not exist, or if it is not otherwise legal to update.
The ELSE clause is taken if the variable cannot be updated for any reason
See also the VARTYPE, VARVAL and VARVALTYPE functions.