def GetStartingGapLength(sequence):
	"""
	This function takes in a sequence, and counts from the beginning how many 
	gaps exist at the beginning of that sequence, up till the first ATG (start
	codon).

	Parameters:
	- sequence: a string along which you wish to count the number of gaps
	"""
	gaps = 0
	for i, position in enumerate(sequence):
		if sequence[i:i+3] == 'ATG':
			break
		elif sequence[i] == '-':
			gaps += 1
		else:
			pass

	return gaps