def make_indicator_node(operator, nid=None):
if operator.upper() not in VALID_INDICATOR_OPERATORS:<EOL><INDENT>raise ValueError('<STR_LIT>'.format(VALID_INDICATOR_OPERATORS))<EOL><DEDENT>i_node = et.Element('<STR_LIT>')<EOL>if nid:<EOL><INDENT>i_node.attrib['<STR_LIT:id>'] = nid<EOL><DEDENT>else:<EOL><INDENT>i_node.attrib['<STR_LIT:id>'] = ioc_et.get_guid()<EOL><DEDENT>i_node.attrib['<STR_LIT>'] = operator.upper()<EOL>return i_node<EOL>
This makes a Indicator node element.  These allow the construction of a logic tree within the IOC.

:param operator: String 'AND' or 'OR'.  The constants ioc_api.OR and ioc_api.AND may be used as well.
:param nid: This is used to provide a GUID for the Indicator. The ID should NOT be specified under normal circumstances.
:return: elementTree element