def find_otu(otuid, tree):
for m in re.finditer(otuid, tree):<EOL><INDENT>before, after = tree[m.start()-<NUM_LIT:1>], tree[m.start()+len(otuid)]<EOL>if before in ["<STR_LIT:(>", "<STR_LIT:U+002C>", "<STR_LIT:)>"] and after in ["<STR_LIT::>", "<STR_LIT:;>"]:<EOL><INDENT>return m.start()<EOL><DEDENT><DEDENT>return None<EOL>
Find an OTU ID in a Newick-format tree.
Return the starting position of the ID or None if not found.