From Bright Pattern Documentation
Integer Expressions
Numbers can have the unary minus operator, e.g., -2
The four arithmetic operations and parentheses, including nested ones, are supported, e.g., (2+3)*((7-1)/2+1)
Division by zero produces error in the log; the operation result is undefined.
Strings cannot be mixed in one expression with numbers, e.g., =2 + “string” is invalid