Genetic sequence
================

A genetic sequence (DNA sequence) can be represented by a string with
a sequence of capital letters A, C, G and T that represent
nucleotides 
`1 <https://en.wikipedia.org/wiki/Nucleic_acid_sequence>`__.

Save all functions into the same file named ``dna.py``.

#. Write function :py:func:`isdna` that takes a string (:class:`str`), and
   returns ``True`` if it is a DNA or ``False`` otherwise. See the
   following examples:
   
   .. literalinclude:: test-isdna.txt
      :language: python3
      :lines: 3-
             
   .. note::

       More tests are provided in the :download:`test-isdna.txt<test-isdna.txt>` file.

#. Write function :py:func:`similar_dna` that takes two strings
   (:class:`str`) with the same length and with a dna each, and
   returns the percentage (:class:`float`) of matching pairs with
   respect to the total length. A matching pair is a pair of
   nucleotides one in each sequence which are equal and at the same
   position. See the following examples:
   
   .. literalinclude:: test-similar.txt
      :language: python3
      :lines: 3-
             
   .. note::

       More tests are provided in the
       :download:`test-similar.txt<test-similar.txt>` file.
   
.. rubric:: Solution
      
A solution of these functions is provided in the
:download:`dna.py<solutions/dna.py>` file.