Contract Names
==============

We wish to *contract* two given names, both composed of letters (at least one) but they do not necessarily have the same length.
We define the string *s* to be the *contraction* of strings *s1*, *s2* if and only if:

    #. s1 is a *prefix* of s
    #. s2 is a *sufix* of s
    #. it is the *sortest* (among those the fulfill the two previous conditions)

For instance, ``'rosandra'`` is a contraction of ``'rosa'`` and ``'sandra'``. But ``'mymamamy'`` is not the contraction of ``'myma'``, ``'mamy'`` (yet it satisfies conditions #1 and #2) since ``'mymamy'`` also does but it is shorter.

You are required to deliver the following function in the module :mod:`contract` (file :file:`contract.py`):

    .. py:function:: contract(n1, n2)

such that

    **given** *n1*, *n2*, non-empty :class:`str` of lowercase letters.

    **returns** a :class:`str` with the contraction of *n1* and *n2* as as described above.

For example:

    .. literalinclude:: contract.test
        :language: python3
        :start-after: --ini
        :end-before: --fi

Doctests are available in the :download:`contract.test` file.