Buggy python submission (verdict: Runtime Error):
r1,c1,r2,c2 = map(int, input().split())
def find_power(n,mod=10**9+7):
    powlist=[0]*(n+1)
    powlist[0]=1
    powlist[1]=1
    for i in range(2,n+1):
        powlist[i]=powlist[i-1]*i%(mod)
    return powlist

def find_inv_power(n,mod=10**9+7):
    powlist=find_power(n)
    check=powlist[-1]
    first=1
    uselist=[0]*(n+1)
    secondlist=[0]*30
    secondlist[0]=check
    secondlist[1]=check**2
    for i in range(28):
        secondlist[i+2]=(secondlist[i+1]**2)%(10**9+7)
    a=format(10**9+5,"b")
    for j in range(30):
        if a[29-j]=="1":
            first=(first*secondlist[j])%(10**9+7)
    uselist[n]=first
    for i in range(n,0,-1):
        uselist[i-1]=(uselist[i]*i)%(10**9+7)
    return uselist

mod = 10**9+7
NUM = (10**6)+100
p_lis=find_power(NUM,mod)
ip_lis=find_inv_power(NUM,mod)

def comb(n,r,mod=10**9+7):
    if n<r:
        return 0
    elif n>=r:
        return (p_lis[n]*ip_lis[r]*ip_lis[n-r])%(mod)
def g(x,y):
    return comb(x+y+2,y+1)-1

ans=g(r2,c2) - g(r1-1,c2) - g(r2,c1-1) + g(r1-1,c1-1)
mod=10**9+7
print(ans%mod)

Fixed submission:
r1,c1,r2,c2 = map(int, input().split())
def find_power(n,mod=10**9+7):
    powlist=[0]*(n+1)
    powlist[0]=1
    powlist[1]=1
    for i in range(2,n+1):
        powlist[i]=powlist[i-1]*i%(mod)
    return powlist

def find_inv_power(n,mod=10**9+7):
    powlist=find_power(n)
    check=powlist[-1]
    first=1
    uselist=[0]*(n+1)
    secondlist=[0]*30
    secondlist[0]=check
    secondlist[1]=check**2
    for i in range(28):
        secondlist[i+2]=(secondlist[i+1]**2)%(10**9+7)
    a=format(10**9+5,"b")
    for j in range(30):
        if a[29-j]=="1":
            first=(first*secondlist[j])%(10**9+7)
    uselist[n]=first
    for i in range(n,0,-1):
        uselist[i-1]=(uselist[i]*i)%(10**9+7)
    return uselist

mod = 10**9+7
NUM = (2*10**6)+100
p_lis=find_power(NUM,mod)
ip_lis=find_inv_power(NUM,mod)

def comb(n,r,mod=10**9+7):
    if n<r:
        return 0
    elif n>=r:
        return (p_lis[n]*ip_lis[r]*ip_lis[n-r])%(mod)
def g(x,y):
    return comb(x+y+2,y+1)-1

ans=g(r2,c2) - g(r1-1,c2) - g(r2,c1-1) + g(r1-1,c1-1)
print(ans%mod)

Buggy python submission (verdict: Time Limit Exceeded):
r1,c1,r2,c2 = map(int, input().split())

def modinv(a, mod=10**9+7):
    return pow(a, mod-2, mod)

def comb(n, r, mod=10**9+7):
    r = min(r, n-r)
    res = 1
    for i in range(r):
        res = res * (n - i) * modinv(i+1, mod) % mod
    return res

def g(x,y):
    return comb(x+y+2,y+1)-1

ans=g(r2,c2) - g(r1-1,c2) - g(r2,c1-1) + g(r1-1,c1-1)

mod=10**9+7
print(ans%mod)

Fixed submission:
r1,c1,r2,c2 = map(int, input().split())
def find_power(n,mod=10**9+7):
    powlist=[0]*(n+1)
    powlist[0]=1
    powlist[1]=1
    for i in range(2,n+1):
        powlist[i]=powlist[i-1]*i%(mod)
    return powlist

def find_inv_power(n,mod=10**9+7):
    powlist=find_power(n)
    check=powlist[-1]
    first=1
    uselist=[0]*(n+1)
    secondlist=[0]*30
    secondlist[0]=check
    secondlist[1]=check**2
    for i in range(28):
        secondlist[i+2]=(secondlist[i+1]**2)%(10**9+7)
    a=format(10**9+5,"b")
    for j in range(30):
        if a[29-j]=="1":
            first=(first*secondlist[j])%(10**9+7)
    uselist[n]=first
    for i in range(n,0,-1):
        uselist[i-1]=(uselist[i]*i)%(10**9+7)
    return uselist

mod = 10**9+7
NUM = (2*10**6)+100
p_lis=find_power(NUM,mod)
ip_lis=find_inv_power(NUM,mod)

def comb(n,r,mod=10**9+7):
    if n<r:
        return 0
    elif n>=r:
        return (p_lis[n]*ip_lis[r]*ip_lis[n-r])%(mod)
def g(x,y):
    return comb(x+y+2,y+1)-1

ans=g(r2,c2) - g(r1-1,c2) - g(r2,c1-1) + g(r1-1,c1-1)
print(ans%mod)