@staticmethod
def fix_value_null(value):
    """Fix <null> values in some Jira parameters.

        In some values fields, as returned by the Jira API,
        some fields appear as <null>. This function convert Them
        to None.

        :param value: string found in a value fields
        :return: same as value, or None
        """
    if value == '<null>':
        return None
    else:
        return value
