PrintError is a utility function that prints a list of errors to w, one error per line, if the err parameter is an ErrorList.

return comments as COMMENT tokens.

In an ErrorList, an error is represented by an *Error.

A Scanner holds the scanner's internal state while processing a given text.

An ErrorHandler may be provided to Scanner.Init.

ErrorList is a list of *Errors.

A mode value is a set of flags (or 0).