//! Low-level **coil driver** trait used by the high-level [Stepper](`crate::stepper::Stepper`).
//!
//! Implement this for your motor wiring to describe how each `this_step`
//! energizes pins. Errors bubble up from the underlying GPIO pins via
//! the associated `Error` type.
//!
//! Equivalent to the Arduino `stepMotor` function.
/// Generic stepper “coil driver” interface (no_std, embedded-hal compatible).