code: public Matrix4x3f set3x3(Matrix4x3fc mat) {
          if (mat instanceof Matrix4x3f) {
              MemUtil.INSTANCE.copy3x3((Matrix4x3f) mat, this);
          } else {
              set3x3Matrix4x3fc(mat);
          }
          properties &= mat.properties();
          return this;
      }
docs: Set the left 3x3 submatrix of this {@link Matrix4x3f} to that of the given {@link Matrix4x3fc}
  and don't change the other elements.
  
  @param mat
  the {@link Matrix4x3fc}
  @return this