Add command is used to add a number to any number value in a chunk or variable.
Built-in Message handler[]
For example all the following expressions are valid:
add 1 to temp
add 2 to field "Temp"
add 3 to item 2 of temp
add 4 to char 3 of temp
add 5 to word 2 of temp
add temp to last line of temp2
