def _do_relation(self):
if self.chunks:<EOL><INDENT>ch = self.chunks[-<NUM_LIT:1>]<EOL>for relation, role in ch.relations:<EOL><INDENT>if role == "<STR_LIT>" or role == "<STR_LIT>":<EOL><INDENT>self.relations[role][relation] = ch<EOL><DEDENT><DEDENT>if ch.type in ("<STR_LIT>",):<EOL><INDENT>self.relations[ch.type][ch.relation] = ch<EOL><DEDENT><DEDENT>
Attaches subjects, objects and verbs.
            If the previous chunk is a subject/object/verb, it is stored in Sentence.relations{}.