Returns a list of variables.
        Each variable is represented by an index of list.
        For example if the no of variables are 4 then the list will be
        [var_0, var_1, var_2, var_3]

        Returns
        -------
        list: list of variables

        Example
        -------
        >>> reader = UAIReader('TestUAI.uai')
        >>> reader.get_variables()
        ['var_0', 'var_1', 'var_2']

def get_variables(self):
        """
        Returns a list of variables.
        Each variable is represented by an index of list.
        For example if the no of variables are 4 then the list will be
        [var_0, var_1, var_2, var_3]

        Returns
        -------
        list: list of variables

        Example
        -------
        >>> reader = UAIReader('TestUAI.uai')
        >>> reader.get_variables()
        ['var_0', 'var_1', 'var_2']
        """
        variables = []
        for var in range(0, self.no_variables):
            var_name = "var_" + str(var)
            variables.append(var_name)
        return variables