def change_custom_contact_var(self, contact, varname, varvalue):
        """Change custom contact variable
        Format of the line that triggers function call::

        CHANGE_CUSTOM_CONTACT_VAR;<contact_name>;<varname>;<varvalue>

        :param contact: contact to edit
        :type contact: alignak.objects.contact.Contact
        :param varname: variable name to change
        :type varname: str
        :param varvalue: variable new value
        :type varvalue: str
        :return: None
        """
        if varname.upper() in contact.customs:
            contact.modified_attributes |= DICT_MODATTR["MODATTR_CUSTOM_VARIABLE"].value
            contact.customs[varname.upper()] = varvalue
            self.send_an_element(contact.get_update_status_brok())
Change custom contact variable
        Format of the line that triggers function call::

        CHANGE_CUSTOM_CONTACT_VAR;<contact_name>;<varname>;<varvalue>

        :param contact: contact to edit
        :type contact: alignak.objects.contact.Contact
        :param varname: variable name to change
        :type varname: str
        :param varvalue: variable new value
        :type varvalue: str
        :return: None