# Basics
## Operators
Math: `+, -, *, /`

## Wire
Wire is directional. We often use `assign lhs = rhs` drive the right signal to left. This assignment is a **continuous**(the change of right will conducted to left immediately when the voltage change), it's not a one-time assignment.
The port(input and output) on a module also have a direction.
When the module become complex, we will declare a wire in the module `wire wire_name;`.
