Here is my problem:

I have a list of tuples (a,b,c) and I want to find the index of the first tuple that starts with a given 'a' and 'b'.

Example:

list = [(1,2,3), (3,4,5), (5,6,7)]

I want, given a = 1, and b = 2 something that returns 0 (index of (1,2,3))

Here is a solution I've found but it's very inefficient:

```
index0(list)  # returns a list of all first elements in tuples
index1(list)  # returns a list of all second elements in tuples
try:
    i = index0.index(a)
    j = index1.index(b)
    if i == j:
          print(i)

```