Eval
====

Let's consider the evaluation of expressions formed from the 4 arithmetic operadors on float vales. For example, the result of evaluating 0.0+5.0-1.0+2.0-3.0 is 3.0.

You are required to implement the following functions in the module :mod:`eval_module` (file :file:`eval_module.py`):

The first function is

    .. py:function:: eval_op(v1, op, v2)

such that
  
    **given** *v1*, *v2* both :class:`float` and *op* a :class:`str`

    **returns** two values:

    - a :class:`bool` which is ``True`` if and only if *op* one of the following :class:`str`: ``'+'``, ``'-'`` , ``'*'`` , ``'/'`` and, if it is ``'/'`` *v2* must not be ``0.0``, and is ``False`` otherwise.

    - a :class:`float` rounded to 1 decimal with either:

      - the result from applying the operator  *op* to ``v1`` i ``v2``, if the previous value is ``True``
      - or ``v1``, if the previous value is ``False``.

For example:

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

Doctests are available in the :download:`eval_op.test` file.
        
-----------------------------------------------------------------------------------

Once `eval_op` is ready, the second function required is

    .. py:function:: eval(val0, op1, val1, op2, val2, op3, val3, op4, val4)

such that
  
    **given** 9 parameters where all *valX* are :class:`float` and all *opX* are :class:`str`

    **returns** two values:

    - a :class:`bool` such that is ``True`` if all the operations succeeded and ``False`` otherwise.

    - a :class:`float` such that it is either:

      - ``val0`` if the previous value is ``False``
      - the result from operating ``val0`` with the 4 arithmetic operations and the value next to it in left to right order.
    
    This function **must** call the previous function.

Per exemple:

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

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