def _parse_life_span_string(life_span_string):
 try:
  life_span = int(life_span_string)
 except:
  life_span = _convert_life_span_string(life_span_string)
 if (life_span <= 0):
  raise Exception('Life span must be greater than 0')
 return life_span

def _parse_life_span_string ( life_span_string ) : try : life_span = int ( life_span_string ) except : life_span = _convert_life_span_string ( life_span_string ) if ( life_span <= 0 ) : raise Exception ( 'Life span must be greater than 0' ) return life_span
parses a life span string .