code: public SDVariable size(String name, SDVariable in) {
          SDVariable ret = f().size(in);
          return updateVariableNameAndReference(ret, name);
      }
docs: Returns the size (number of elements, i.e., prod(shape)) of the specified SDVariable as a 0D scalar variable
  
  @param name Name of the output variable
  @param in   Input variable
  @return 0D (scalar) output variable with value equal to the number of elements in the specified array