Buggy python submission (verdict: Time Limit Exceeded):
N=int(input())

E=[[] for i in range(N+1)]

for i in range(N-1):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

mod=10**9+7

from collections import deque
Q=deque()

USE=[0]*(N+1)
Q.append(1)
H=[0]*(N+1)
H[1]=1
USE[1]=1

while Q:
    x=Q.pop()
    for to in E[x]:
        if USE[to]==0:
            USE[to]=1
            H[to]=H[x]+1
            Q.append(to)

EH=[(h,ind+1) for ind,h in enumerate(H[1:])]
EH.sort(reverse=True)

COME=[1]*(N+1)
USE=[0]*(N+1)

for h,ind in EH:
    USE[ind]=1
    for to in E[ind]:
        if USE[to]==0:
            COME[to]+=COME[ind]

ANS=0
for i in range(1,N+1):
    SCORE=[]
    for j in E[i]:
        if COME[j]<COME[i]:
            SCORE.append(COME[j])

    if sum(SCORE)<N-1:
        SCORE.append(N-sum(SCORE)-1)

    AV=1

    for s in SCORE:
        AV+=pow(2,s,mod)-1

    ANS+=pow(2,N-1,mod)-AV
    #print(SCORE,AV)

print((ANS*pow(pow(2,N,mod),mod-2,mod))%mod)

Fixed submission:
N=int(input())

E=[[] for i in range(N+1)]

for i in range(N-1):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

mod=10**9+7

from collections import deque
Q=deque()

USE=[0]*(N+1)
Q.append(1)
H=[0]*(N+1)
H[1]=1
USE[1]=1

while Q:
    x=Q.pop()
    for to in E[x]:
        if USE[to]==0:
            USE[to]=1
            H[to]=H[x]+1
            Q.append(to)

EH=[(h,ind+1) for ind,h in enumerate(H[1:])]
EH.sort(reverse=True)

COME=[1]*(N+1)
USE=[0]*(N+1)

for h,ind in EH:
    USE[ind]=1
    for to in E[ind]:
        if USE[to]==0:
            COME[to]+=COME[ind]

ANS=0

POW2=[1]
for i in range(N+1):
    POW2.append(POW2[-1]*2%mod)

for i in range(1,N+1):
    SCORE=[]
    for j in E[i]:
        if COME[j]<COME[i]:
            SCORE.append(COME[j])

    if sum(SCORE)<N-1:
        SCORE.append(N-sum(SCORE)-1)

    AV=1

    for s in SCORE:
        AV+=POW2[s]-1

    ANS+=POW2[N-1]-AV
    #print(SCORE,AV)

print((ANS*pow(POW2[N],mod-2,mod))%mod)

Buggy python submission (verdict: Time Limit Exceeded):
N=int(input())

E=[[] for i in range(N+1)]

for i in range(N-1):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

mod=10**9+7

from collections import deque
Q=deque()

USE=[0]*(N+1)
Q.append(1)
H=[0]*(N+1)
H[1]=1
USE[1]=1

while Q:
    x=Q.pop()
    for to in E[x]:
        if USE[to]==0:
            USE[to]=1
            H[to]=H[x]+1
            Q.append(to)

EH=[(h,ind+1) for ind,h in enumerate(H[1:])]
EH.sort(reverse=True)

COME=[1]*(N+1)
USE=[0]*(N+1)

for h,ind in EH:
    USE[ind]=1
    for to in E[ind]:
        if USE[to]==0:
            COME[to]+=COME[ind]

ANS=0
for i in range(1,N+1):
    SCORE=[]
    for j in E[i]:
        if COME[j]<COME[i]:
            SCORE.append(COME[j])

    if sum(SCORE)<N-1:
        SCORE.append(N-sum(SCORE)-1)

    AV=1

    for s in SCORE:
        AV+=pow(2,s,mod)-1

    ANS+=pow(2,N-1,mod)-AV
    #print(SCORE,AV)

print((ANS*pow(pow(2,N,mod),mod-2,mod))%mod)

Fixed submission:
N=int(input())

E=[[] for i in range(N+1)]

for i in range(N-1):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

mod=10**9+7

from collections import deque
Q=deque()

USE=[0]*(N+1)
Q.append(1)
H=[0]*(N+1)
H[1]=1
USE[1]=1

while Q:
    x=Q.pop()
    for to in E[x]:
        if USE[to]==0:
            USE[to]=1
            H[to]=H[x]+1
            Q.append(to)

EH=[(h,ind+1) for ind,h in enumerate(H[1:])]
EH.sort(reverse=True)

COME=[1]*(N+1)
USE=[0]*(N+1)

for h,ind in EH:
    USE[ind]=1
    for to in E[ind]:
        if USE[to]==0:
            COME[to]+=COME[ind]

ANS=0

POW2=[1]
for i in range(N+1):
    POW2.append(POW2[-1]*2%mod)

for i in range(1,N+1):
    SCORE=[]
    for j in E[i]:
        if COME[j]<COME[i]:
            SCORE.append(COME[j])

    if sum(SCORE)<N-1:
        SCORE.append(N-sum(SCORE)-1)

    AV=1

    for s in SCORE:
        AV+=POW2[s]-1

    ANS+=POW2[N-1]-AV
    #print(SCORE,AV)

print((ANS*pow(POW2[N],mod-2,mod))%mod)