def copy(app, need, needs, option, need_id=None):
if need_id is not None:<EOL><INDENT>need = needs[need_id]<EOL><DEDENT>return need[option]<EOL>
Copies the value of one need option to another

.. code-block:: jinja

    .. req:: copy-example
       :id: copy_1
       :tags: tag_1, tag_2, tag_3
       :status: open

    .. spec:: copy-example implementation
       :id: copy_2
       :status: [[copy("status", "copy_1")]]
       :links: copy_1
       :comment: [[copy("id")]]

       Copies status of ``copy_1`` to own status.
       Sets also a comment, which copies the id of own need.

    .. test:: test of specification and requirement
       :id: copy_3
       :links: copy_2; [[copy('links', 'copy_2')]]
       :tags: [[copy('tags', 'copy_1')]]

       Set own link to ``copy_2`` and also copies all links from it.

       Also copies all tags from copy_1.

.. req:: copy-example
   :id: copy_1
   :tags: tag_1, tag_2, tag_3
   :status: open

.. spec:: copy-example implementation
   :id: copy_2
   :status: [[copy("status", "copy_1")]]
   :links: copy_1
   :comment: [[copy("id")]]

   Copies status of ``copy_1`` to own status.
   Sets also a comment, which copies the id of own need.

.. test:: test of specification and requirement
   :id: copy_3
   :links: copy_2; [[copy('links', 'copy_2')]]
   :tags: [[copy('tags', 'copy_1')]]

   Set own link to ``copy_2`` and also copies all links from it.

   Also copies all tags from copy_1.

:param option: Name of the option to copy
:param need_id: id of the need, which contains the source option. If None, current need is taken
:return: string of copied need option