anchor.diff:  const ParserErrorCode _MISSING_PREFIX_IN_DEFERRED_IMPORT =
       const ParserErrorCode('MISSING_PREFIX_IN_DEFERRED_IMPORT',
           r"Deferred imports should have a prefix.",
  -        correction: "Try adding a prefix to the import.");
  +        correction:
  +            "Try adding a prefix to the import by adding an 'as' clause.");
   
   const ParserErrorCode _MISSING_STATEMENT =
       const ParserErrorCode('MISSING_STATEMENT', r"Expected a statement.");
  
positive.code: 
  const ParserErrorCode _EQUALITY_CANNOT_BE_EQUALITY_OPERAND = const ParserErrorCode(
      'EQUALITY_CANNOT_BE_EQUALITY_OPERAND',
      r"An equality expression can't be an operand of another equality expression.",
      correction: "Try re-writing the expression.");
  
  const ParserErrorCode _EXPECTED_BODY = const ParserErrorCode(
      'EXPECTED_BODY', r"A #string must have a body, even if it is empty.",
  
negative.code: 
  const ParserErrorCode _EXTERNAL_FIELD = const ParserErrorCode(
      'EXTERNAL_FIELD', r"Fields can't be declared to be 'external'.",
      correction:
          "Try removing the keyword 'external', or replacing the field by an external getter and/or setter.");
  
  const ParserErrorCode _EXTERNAL_METHOD_WITH_BODY = const ParserErrorCode(
      'EXTERNAL_METHOD_WITH_BODY',
  