static Node circular ( Node head ) {
  Node start = head ;
  while ( head . next != null ) head = head . next ;
  head . next = start ;
  return start ;
}

static Node circular ( Node head ) { Node start = head ; while ( head . next != null ) head = head . next ; head . next = start ; return start ; }
(method_declaration (modifiers) type: (type_identifier) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (identifier))) (while_statement condition: (parenthesized_expression (binary_expression left: (field_access object: (identifier) field: (identifier)) right: (null_literal))) body: (expression_statement (assignment_expression left: (identifier) right: (field_access object: (identifier) field: (identifier))))) (expression_statement (assignment_expression left: (field_access object: (identifier) field: (identifier)) right: (identifier))) (return_statement (identifier))))