the error handling of cgi.FieldStorage

Question

I want to ask about the error handling of cgi.FieldStorage() https://docs.python.org/2/library/cgi.html I have reference the exmaple to write my program below is my program

arg = cgi.FieldStorage()
if "s_d" not in arg or "e_d" not in arg:
   print "no valid input"
   return 
else:
   s_date = arg["s_d"].value
   e_date = arg["e_d"].value

print s_date
print type(s_date)
print e_date
print type(e_date)

It works when I click below URI http: / /hostname/test.py?s_d=%272015-01-01%27&e_d=%272015-02-01%27

When I want to try the error handling, it failed http: / /hostname/test.py

The error log is like below

File "test.py", line 152
    return 
SyntaxError: 'return' outside function
Premature end of script headers: test.py

I want to protect my program. Make it can go with no parameter or whatever parameters. Please advice. many thanks

Answer 1

yes , thanks for @Forge 's suggestion I write my program again, it is cool now.

arg = cgi.FieldStorage()
    s_date = ''
    e_date = ''
    def get_parameter():
        global s_date,e_date
        if "s_d" not in arg or "e_d" not in arg:
           print "no valid input"
           return
        else:
           s_date = arg["s_d"].value
           e_date = arg["e_d"].value
    get_parameter()