IsMatchError returns true if err is a MatchError, false otherwise.

IsSyntaxError returns true if err is a syntax error, false otherwise.

NewMatchError creates a new MatchError object.

IncompleteOperatorError represents an incomplete operator that was found when parsing the expression.

MatchError represents the case when the input tokens did not match a given parser.

UnknownTokenError represents an unknown token that was found when parsing the expression.