code: def _init_compile_patterns(optional_attrs):
          
          attr2cmp = {}
          if optional_attrs is None:
              return attr2cmp
          # "peptidase inhibitor complex" EXACT [GOC:bf, GOC:pr]
          # "blood vessel formation from pre-existing blood vessels" EXACT systematic_synonym []
          # "mitochondrial inheritance" EXACT []
          # "tricarboxylate transport protein" RELATED [] {comment="WIkipedia:Mitochondrial_carrier"}
          if 'synonym' in optional_attrs:
              attr2cmp['synonym'] = re.compile(r'"(\S.*\S)" ([A-Z]+) (.*)\[(.*)\](.*)$')
              attr2cmp['synonym nt'] = cx.namedtuple("synonym", "text scope typename dbxrefs")
          # Wikipedia:Zygotene
          # Reactome:REACT_27267 "DHAP from Ery4P and PEP, Mycobacterium tuberculosis"
          if 'xref' in optional_attrs:
              attr2cmp['xref'] = re.compile(r'^(\S+:\s*\S+)\b(.*)$')
          return attr2cmp
docs: Compile search patterns for optional attributes if needed.