Safe column breakdown with coanc subcommand

[lavanyarishishwar]

Error to address:

Traceback (most recent call last):
File "./pastrami.py", line 1899, in
analysis.go()
File "./pastrami.py", line 492, in go
function()
File "./pastrami.py", line 1069, in build_coanc
this_chromosome, left_snp, right_snp = chromosome_haplotypes.iloc[this_haplotype, :]
ValueError: too many values to unpack (expected 3)