def eval_parallel(parse_result):
 if (len(parse_result) == 1):
  return parse_result[0]
 if (0 in parse_result):
  return float('nan')
 reciprocals = [(1.0 / e) for e in parse_result if isinstance(e, numbers.Number)]
 return (1.0 / sum(reciprocals))

def eval_parallel ( parse_result ) : if ( len ( parse_result ) == 1 ) : return parse_result [ 0 ] if ( 0 in parse_result ) : return float ( 'nan' ) reciprocals = [ ( 1.0 / e ) for e in parse_result if isinstance ( e , numbers . Number ) ] return ( 1.0 / sum ( reciprocals ) )
compute numbers according to the parallel resistors operator .