You sir, are completely right.

Fixed:
Code:
def Primes(l,u,p):
    if l<2:
        l=2
    if u<2:
        return
    u+=1
    for i in range(l,u):
        f=True
        for x in range(2,u):
            if i%x==0 and i!=x and i>x:
                f=False
        if f and i>=l:
            p.append(i)
    return p
Added about 7 characters: 140 total