i need if condition to detect whether it is last element of the column in csv file to not add “,” /pyhton

Question

f=open(\'students.csv\', \'r\') 
a=f.readline() 
length=len(a.split(","))
fw=open(\'output.csv\', \'w\')
lst = []
while a: 
   lst.append(a)
   a=f.readlin