public static boolean isValid ( char c ) {
  if ( c == 'A' || c == 'C' || c == 'T' || c == 'G' ) {
    return true ;
  }
  return false ;
}

public static boolean isValid ( char c ) { if ( c == ' A ' || c == ' C ' || c == ' T ' || c == ' G ' ) { return true ; } return false ; }
(method_declaration (modifiers) type: (boolean_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (character_literal)) right: (binary_expression left: (identifier) right: (character_literal))) right: (binary_expression left: (identifier) right: (character_literal))) right: (binary_expression left: (identifier) right: (character_literal)))) consequence: (block (return_statement (true)))) (return_statement (false))))