Reverse Polish Notation🔗 i

Reverse Polish Notation (RPN) is a way of writing expressions commonly found in calculators and Forth-like programming languages. In RPN, an expression is a list of instructions for manipulating data on a stack. The most basic instruction is to push a value onto the stack. Function call instructions pop a function’s arguments off the stack and push its results onto the stack. The rpn library represents an RPN program as a call to the rpn function with the program instructions as arguments.