prime checker in python

1def isPrime(n):
2  if n<2:		#1, 0 and all negative numbers are not prime
3    return False
4  elif n==2:	#2 is prime but cannot be calculated with the formula below becuase of the range function
5    return True
6  else:
7    for i in range(2, n):
8      if (n % i) == 0:	#if you can precisely divide a number by another number, it is not prime
9        return False
10    return True			#if the progam dont return False and arrives here, it means it has checked all the numebrs smaller than n and nono of them divides n. So n is prime

1#make the function
2#to do this all hte vairibles go in side the function
3
4def CheckIfPrime ():
5    a1 = input("which number do you want to check")
6    a = int(a1)#you need the checking number as an int not an str
7    b = 2 #the number to check againts
8    c = ("yes")
9    while b < a:#run the loop
10        if a%b == 0:#check if the division has a remainder
11            c = ("no")#set the answer
12        b = b+1
13    print(c)#print the output
14CheckIfPrime ()#call the function  
15