Pupil Code _String Slicing

"""
 01  function pupilcode(year,…………………… ,……………………)
 02          yrpart = year.subString(2,2)
 03          snpart = surname.subString(0,……………………)
 04          fnpart = firstname.subString(0,1)
 05           …………………  yrpart + snpart.lower + fnpart.lower
"""
def pupilcode(year,surname, firstname):
    yrpart = year[2:4] #0123 => 23
    snpart = surname.lower()[0:5] #"colin gwood"
    fnpart = firstname.lower()[0:1] # first letter
    return yrpart+snpart+fnpart

#print(pupilcode("2021","Bloggs","Fred"))

year_input = input("Enter year >> ")
sname_input = input("Enter sname >> ")
fname_input = input("Enter fname >> ")

print(pupilcode(year_input,sname_input,fname_input))

pupilcodecreated = pupilcode(year_input,sname_input,fname_input)

file = open("pupilcodes.txt","a") # r read only, w write
file.write(pupilcodecreated +"\n") # \n adds a new line
file.close()