pub trait RealToComplex<T>: Send + Sync {
// Required methods
fn process(
&self,
input: &mut [T],
output: &mut [Complex<T>],
) -> Result<(), FftError>;
fn make_input_vec(&self) -> Vec<T>;
fn make_output_vec(&self) -> Vec<Complex<T>>;
fn len(&self) -> usize;
// Provided method
fn is_empty(&self) -> bool { ... }
}