Finding the Next Prime Number

def isprime(n):
    for i in range(2,n):
        if n%i == 0:
            return False
    else:
        return True

def nextprime(n):
    T1 = ()

    for i in range(n,n+100):
        if (isprime(i) and i > n):
            return i

val = nextprime(3)
print(val)