def get_shebang(tokens):
<EOL>for tok in tokens[<NUM_LIT:0>:<NUM_LIT:4>]: <EOL><INDENT>line = tok[<NUM_LIT:4>]<EOL>if shebang.match(line): <EOL><INDENT>return line<EOL><DEDENT><DEDENT>
Returns the shebang string in *tokens* if it exists.  None if not.