**Background**

I have a nested list. In each sublist are four 1s or 0s identifying survival (living or dead) for a specimen. When a specimen is born they go from 0 to 1, a specimen death goes from 1 to 0.

**Problem**

Because specimens can't come back from the dead I need to identify where a specimen was 1, went to 0 at least once and then back to 1.

**Current Solution**

Because the list always has exactly 4 entries (each representing a year where their living or dead status was observed), I've hard-coded a solution based on comparing the entries with if/else but it is very inelegant and would require exponentially more if/else statements if the data is collected another year.

Is there a better way?

**Short, Self Contained, Compilable Example**

```
#Sample list
my_list = [[1,1,1,1], #no issue, survived 4 years
       [1,1,0,1], #data quality issue, died and then born again
       [1,0,0,1], #data quality issue, died and then born again    
       [0,0,0,1], #no issue, born in 4th year
       [1,0,0,0]] #no issue, died after 1st year

#Iterate through the list
for each in my_list:
    if ((each[0] == 1) and (each[1] == 1)) and (each[2] == 0) and (each[3] == 1):
        print(str(each) + ' has data quality issues')
    if ((each[0] == 1) and (each[1] == 0)) and (each[2] == 1):
        print(str(each) + ' has data quality issues')
    if ((each[1] == 0) and (each[2] == 0)) and (each[3] == 1):
        if each[0] == 0:
            pass #do nothing
        else:
            print(str(each) + ' has data quality issues')

```

**Output**

```
[1, 1, 0, 1] has data quality issues
[1, 0, 0, 1] has data quality issues

```