def genome_dic(g_file):
	"""
	Make a dictionary of chromosome sizes from a .chrom.sizes file
	e.g. {chrom_name:chrom_size}
	"""
	gdict = {}
	with open(g_file) as ifile:
		for i in ifile:
			i = i.split()
			gdict[i[0]] = int(i[1])
	return gdict