def _get_boundary_condition(bc_type):
	"""Turn full boundary condition names into one boundary condition key
	
	Parameter:
	----------
	:type bc_type: str
	:param bc_type:
		Boundary condition type:
			Vacuum:     'v', 'vacuum', or 'zero-incoming'
			Reflective: 'r', 'reflective', or 'zero-current'
	
	Returns;
	--------
	:rtype: str
	:returns:
		Boundary condition 'v' or 'r'
	"""
	bc_type = bc_type.lower()
	if bc_type in ('v', 'vacuum', 'zero-incoming'):
		return 'v'
	elif bc_type in ('r', 'reflective', 'zero-current'):
		return 'r'
	else:
		errstr = "Unknown boundary condition: {}".format(bc_type)
		raise NotImplementedError(errstr)