assignToken method
Token for the assignment operator =, distinct from ==, :=, += etc.
Implementation
Parser<Token<String>> assignToken() =>
token((char('=') & char('=').not()).flatten(message: '= expected'));
Token for the assignment operator =, distinct from ==, :=, += etc.
Parser<Token<String>> assignToken() =>
token((char('=') & char('=').not()).flatten(message: '= expected'));