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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_cmd(self):
 """Returns the full command to be executed at runtime"""


        cmd = None
        if self.test_program in ('nose', 'nosetests'):
            cmd = "nosetests %s" % self.file_path
        elif self.test_program == 'django':
            executable = "%s/manage.py" % self.file_path
            if os.path.exists(executable):
                cmd = "python %s/manage.py test" % self.file_path
            else:
                cmd = "django-admin.py test"
        elif self.test_program == 'py':
            cmd = 'py.test %s' % self.file_path
        elif self.test_program == 'symfony':
            cmd = 'symfony test-all'
        elif self.test_program == 'jelix':
            # as seen on http://jelix.org/articles/fr/manuel-1.1/tests_unitaires
            cmd = 'php tests.php'
        elif self.test_program == 'phpunit':
            cmd = 'phpunit'
        elif self.test_program == 'sphinx':
            cmd = 'make html'
        elif self.test_program == 'tox':
            cmd = 'tox'

        if not cmd:
            raise InvalidTestProgram("The test program %s is unknown. Valid options are: `nose`, `django` and `py`" % self.test_program)

        # adding custom args
        if self.custom_args:
            cmd = '%s %s' % (cmd, self.custom_args)
        return cmd