Newbie question: Why am I getting the too many variables error on my loop index variable?

[freeflow]

I'm currently having a bash at using nim by converting my efforts for Advent of 
Code from VBA to nim. Unfortunately I've got stuck when trying to iterate over 
the input from a file and push that input into an OrderedTable.
    
    
    proc GetDay02Program(): OrderedTable[int64,int64]  =
        for myKey, myValue in  readFile(day02PathAndName).split(','):
            result[myKey.int64]=myValue.parseint.int64
    
    Run

'''

In the code above the myKey variable is flagged and the error message is 'wrong 
number of variables'. I'm a bit perplexed as the reading I've done indicates 
that my for statement is as expected.

I'd appreciate being enlighteded as to why iI'm getting the error.