#NEWLINE# def _sum( self , other , sign1 , sign2 ) : #NEWLINE# #INDENT# if ( not isPhysicalQuantity ( other ) ) : #NEWLINE# #INDENT# raise TypeError ( 'Incompatible types' ) #NEWLINE# #UNINDENT# new_value = ( ( new_value * self . value ) + ( ( sign2 * other . value ) * other . unit . conversionFactorTo ( self . unit ) ) ) #NEWLINE# return self . __class__ ( new_value , self . unit , self . _space )