Phone calls
===========

There are one or more files that contain a sequence of numbers
corresponding to the telephone calls of some office. Each line of the
file contains a single telephone number, corresponding to a call.

As an example, you can download the file
:download:`calls.txt<examples/calls.txt>` that has the following
content:

  .. literalinclude:: examples/calls.txt
     :language: python
		
Save all functions into the same file named ``phone.py``.

#. Write a function :py:func:`ncalls1` that takes the name of a file
   (string) with the given content, and returns how many times the
   number 012 has received a call and how many the
   number 11811. Examples:

   .. literalinclude:: ncalls1.txt
      :language: python3
      :lines: 8-
             
   .. note::

       More tests are provided in file :download:`ncalls1.txt<ncalls1.txt>`
   
#. Write a function :py:func:`ncalls2` that takes the name of a file
   (string) with the given content and the name of an output file, and
   computes how many times the number 012 has received a call and how
   many the number 11811.  The function has to create a new file with
   the name given as second parameter and with two lines. Each line
   will contain the telephone number (012 or 11811) and the number of
   times it has received a call, separated by one whitespace. Examples:

   .. literalinclude:: ncalls2.txt
      :language: python3
      :lines: 8-12
             
   .. note::

       More tests are provided in file :download:`ncalls2.txt<ncalls2.txt>`

#. Write a function :py:func:`consecutive_numbers` that takes the name
   of a file (string) with the decribed content, and
   returns True if there are two equal consecutive
   numbers in the file and False otherwise. Examples:

   .. literalinclude:: consecutive_numbers.txt
      :language: python3
      :lines: 8-9
             
   .. note::

       More tests are provided in file :download:`consecutive_numbers.txt<consecutive_numbers.txt>`
   
#. Write a function :py:func:`prefix` that takes the name of a
   file (string) with the described content, the name of an output
   file (string) and another string corresponding to a prefix. The
   function has to write in the second file those telephone numbers
   in the first file with the given prefix. Examples:

   .. literalinclude:: prefix.txt
      :language: python3
      :lines: 8-
             
   .. note::

       More tests are provided in file :download:`prefix.txt<prefix.txt>`

.. rubric:: Solution
      
A solution of these functions is provided in the
:download:`phone.py<solutions/phone.py>` file.