Series
======

Let's consider the following mathematical succession parameterized by the real number constants :math:`k_1, k_2`:

    .. math:: x_{i+1}  = \left| \frac{k_1 + sin(x_i)}{2*e^{k_2 x_i}} \right|

Implement the following Python functions (following the order is recommended) in the module :mod:`series11` (file :file:`series11.py`).

The first function is:

    ``calc_term``:math:`(k_1, k_2, x_i)`
        | takes :math:`k_1, k_2, x_i` :class:`float` values, where :math:`x_i` is an angle expressed in radians
        | returns :math:`x_{i+1}` according to the above definition, as a :class:`float` rounded to 4 decimals.

For exemple:

   .. literalinclude:: calc_term-test.txt
      :language: python3
      :start-after: --ini
      :end-before: --fi
      
.. note:: Python standard modules such as :mod:`math` **may** be imported and used.

Doctests are available at the :download:`calc_term-test.txt` file.

The second function is:

    ``sum3eventerms``:math:`(k_1, k_2, x_0)`
        | takes :math:`k_1, k_2, x_0` :class:`float` values
        | returns  the addition of the terms :math:`x_0, x_2, x_4` of the above succession, as a :class:`float` value rounded to 3 decimals.

For exemple:

   .. literalinclude:: sum3eventerms-test.txt
      :language: python3
      :start-after: --ini
      :end-before: --fi
      
.. note:: This function implementation **must** call the previous function as many times as needed.

Doctests are available at the :download:`sum3eventerms-test.txt` file.