#NEWLINE# def can_unify( self , other ) : #NEWLINE# #INDENT# ' If the variable can be replaced with other\n        a substitution is returned.\n        ' #NEWLINE# if ( other . is_primitive ( ) or ( not self . _prim_only ) ) : #NEWLINE# #INDENT# return [ ( self , self ) ] #NEWLINE# #UNINDENT# return None