static double sum ( int n ) {
  if ( n == 0 ) return 1 ;
  double ans = 1 / ( double ) Math . pow ( 3 , n ) + sum ( n - 1 ) ;
  return ans ;
}

static double sum ( int n ) { if ( n == 0 ) return 1 ; double ans = 1 / ( double ) Math . pow ( 3 , n ) + sum ( n - 1 ) ; return ans ; }
(method_declaration (modifiers) type: (floating_point_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (return_statement (decimal_integer_literal))) (local_variable_declaration type: (floating_point_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (decimal_integer_literal) right: (cast_expression type: (floating_point_type) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (identifier))))) right: (method_invocation name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (return_statement (identifier))))