def add_lib_elements(array_of_tuples, front = false)
      if front
        @lib_elements = array_of_tuples+lib_elements
      else
        lib_elements.concat(array_of_tuples)
      end
    end
def add_lib_elements(array_of_tuples, front = false)
      if front
        @lib_elements = array_of_tuples+lib_elements
      else
        lib_elements.concat(array_of_tuples)
      end
    end
1. element: type
 2. element: name, must not be a building block