append_pair Subroutine

    subroutine append_pair(pair, name, value)
        
        !!> Appends a new `pair_type` instance with the provided `name` 
        !!> and `value` into the given `pair_type array`(i.e pair).

        type(pair_type), allocatable, intent(inout) :: pair(:)
            !! An array of `pair_type` objects, to which a new instance of `pair_type` needs to be added.
        character(*), intent(in) :: name
            !! The `name` attribute of the `pair_type` to be added.
        character(*), intent(in) :: value
            !! The `value` attribute of the `pair_type` to be added.
        type(pair_type), allocatable :: temp(:)
        integer :: n

        if (allocated(pair)) then
            n = size(pair)
            allocate(temp(n+1))
            temp(1:n) = pair
            temp(n+1) = pair_type(name, value)
            call move_alloc(temp, pair)
        else
            allocate(pair(1))
            pair(1) = pair_type(name, value)
        end if
    end subroutine append_pair