Sum massive

inp_data = [1, 2, 3, 4]

def summ(cou):
     _ = 0
     for i in range(len(cou)): _ += cou[i]
     return _
print(summ(inp_data))

def summ_re(list_, summ=0, index=0):
    if index < len(list_):
       return summ_re(list_, summ+list_[index], index + 1)
    else:
        return summ
print(summ_re(inp_data))

def summ_wh(list_):
    summ = 0
    index = 0
    while index < len(list_):
        summ += list_[index]
        index += 1
    return summ
print(summ_wh(inp_data))