Returns requested attribute value.

        Usage::

            >>> content = ["[Section A]\\n", "; Comment.\\n", "Attribute 1 = \\"Value A\\"\\n", "\\n", \
"[Section B]\\n", "Attribute 2 = \\"Value B\\"\\n"]
            >>> sections_file_parser = SectionsFileParser()
            >>> sections_file_parser.content = content
            >>> sections_file_parser.parse()
            <foundations.parsers.SectionsFileParser object at 0x679302423>
            >>> sections_file_parser.get_value("Attribute 1", "Section A")
            u'Value A'

        :param attribute: Attribute name.
        :type attribute: unicode
        :param section: Section containing the searched attribute.
        :type section: unicode
        :param default: Default return value.
        :type default: object
        :return: Attribute value.
        :rtype: unicode

def get_value(self, attribute, section, default=""):
        """
        Returns requested attribute value.

        Usage::

            >>> content = ["[Section A]\\n", "; Comment.\\n", "Attribute 1 = \\"Value A\\"\\n", "\\n", \
"[Section B]\\n", "Attribute 2 = \\"Value B\\"\\n"]
            >>> sections_file_parser = SectionsFileParser()
            >>> sections_file_parser.content = content
            >>> sections_file_parser.parse()
            <foundations.parsers.SectionsFileParser object at 0x679302423>
            >>> sections_file_parser.get_value("Attribute 1", "Section A")
            u'Value A'

        :param attribute: Attribute name.
        :type attribute: unicode
        :param section: Section containing the searched attribute.
        :type section: unicode
        :param default: Default return value.
        :type default: object
        :return: Attribute value.
        :rtype: unicode
        """

        if not self.attribute_exists(attribute, section):
            return default

        if attribute in self.__sections[section]:
            value = self.__sections[section][attribute]
        elif foundations.namespace.set_namespace(section, attribute) in self.__sections[section]:
            value = self.__sections[section][foundations.namespace.set_namespace(section, attribute)]
        LOGGER.debug("> Attribute: '{0}', value: '{1}'.".format(attribute, value))
        return value