Function add_same 

pub fn add_same<D: Dimension>(
    a: &StringArray<D>,
    b: &StringArray<D>,
) -> FerrayResult<StringArray<D>>

Same-dimension elementwise string concatenation.

Like add but both inputs must have the same shape — no broadcasting is performed, and the result preserves the static dimension type. Use this when you know the shapes match and want to keep StringArray<Ix1> instead of getting StringArray<IxDyn> (#163).

Errors

Returns FerrayError::ShapeMismatch if shapes differ.