Can you help me fix the error in my python code? Right now I am receiving the following error:

The call utils.get_for_id('S00313',students) crashed. Traceback (most recent call last): File "/home/codio/workspace/.guides/tests/step2/verifier.py", line 315, in grade_func1 row = utils.get_for_id(person,table) File "/home/codio/workspace/auditor/utils.py", line 177, in get_for_id ct = id.__class__._cache[id.db][table] AttributeError: type object 'str' has no attribute '_cache' 

This is the function:

import utils

# CERTIFICATION CLASSIFICATIONS

# The certification of this pilot is unknown

PILOT_INVALID = -1

# A pilot that has joined the school, but has not soloed

PILOT_NOVICE= 0

# A pilot that has soloed but does not have a license

PILOT_STUDENT = 1

# A pilot that has a license, but has under 50 hours post license

PILOT_CERTIFIED = 2

# A pilot that 50 hours post license

PILOT_50_HOURS= 3

def get_certification(takeoff,student):

"""

Returns the certification classification for this student at the time of takeoff.

The certification is represented by an int, and must be the value PILOT_NOVICE,

PILOT_STUDENT, PILOT_CERTIFIED, PILOT_50_HOURS, or PILOT_INVALID. It is PILOT_50_HOURS

if the student has certified '50 Hours' before this flight takeoff.It is

PILOT_CERTIFIED if the student has a private license before this takeoff and

PILOT_STUDENT is the student has soloed before this takeoff.A pilot that has only

just joined the school is PILOT_NOVICE.If the flight takes place before the student

has even joined the school, the result is PILOT_INVALID.

Recall that a student is a 10-element list of strings.The first three elements are

the student's identifier, last name, and first name.The remaining elements are all

timestamps indicating the following in order: time joining the school, time of first

solo, time of private license, time of 50 hours certification, time of instrument

rating, time of advanced endorsement, and time of multiengine endorsement.

Parameter takeoff: The takeoff time of this flight

Precondition: takeoff is a datetime object

Parameter student: The student pilot

Precondition: student is 10-element list of strings representing a pilot

"""

cert_ = -1

for item in student[3:]:

if (item is not None) and (item != ''):

time = utils.str_to_time(item)

if time < takeoff and cert_ <= 2:

cert_ +=1

return cert_

This is an example of the data we have to pull from:

ID,LAST NAME,FIRST NAME,JOINED,SOLO,LICENSE,50 HOURS,INSTRUMENT,ADVANCED,MULTIENGINE

S00304,Wilson,Zachary,2015-01-07,2015-03-24,,,,,

S00308,Bates,Ashley,2015-01-09,2015-04-14,,,,,

S00309,Jones,Tammy,2015-01-10,2015-03-30,,,,,

S00311,Wheeler,Michael,2015-01-14,2015-04-08,,,,,

S00313,Kelley,Julie,2015-01-14,2015-03-02,,,,,

S00314,Barrett,Tammy,2015-01-18,2015-06-13,,,,,

S00315,Murray,Donald,2015-01-20,2015-08-29,,,,,

S00319,Holland,Tiffany,2015-01-25,2015-03-09,,,,,

S00321,Coleman,Judith,2015-01-28,2015-07-05,,,,,

S00324,Moreno,Harold,2015-01-29,2015-04-11,,,,,

S00326,Aguilar,Jacob,2015-01-31,2015-03-27,,,,,

S00328,Pearson,Ethan,2015-02-10,2015-03-30,,,,,

S00329,Carpenter,Martha,2015-02-10,2015-09-12,,,,,

S00331,Wilson,Ruth,2015-02-20,2016-02-14,,,,,

S00335,Campbell,Ronald,2015-02-21,2015-04-10,,,,,

S00336,Murphy,Deborah,2015-02-22,2015-08-16,,,,,

S00337,Reid,Ralph,2015-02-24,2015-05-07,,,,,

S00341,Torres,Harold,2015-02-24,2015-04-10,,,,,

S00342,Marshall,Emma,2015-02-24,2015-10-25,,,,,

S00343,Richards,Sean,2015-03-02,2015-11-07,,,,,

S00347,Dixon,Sean,2015-03-04,2015-06-02,,,,,

S00350,Dixon,Henry,2015-03-04,2015-05-28,2015-08-11,2015-12-22,2015-12-22,,

S00352,Munoz,Louis,2015-03-09,2015-08-01,,,,,

S00353,Pena,Christopher,2015-03-11,2015-04-29,2015-06-05,2015-09-08,,,

S00354,Morales,Roy,2015-03-15,2015-04-30,,,,,

S00358,Schultz,Louis,2015-03-15,2016-03-06,,,,,

S00362,Kim,Nathan,2015-03-16,2015-06-23,2015-08-11,2016-01-05,,,

S00365,Pearson,Jose,2015-03-19,2015-08-30,,,,,

S00366,Hayes,David,2015-03-21,2015-12-13,,,,,