Statements

Block statement

blockStmt := '{' decl* '}'

A block is a list of declarations, so you can declare variables in side this statement. We put it between two curly braces.

Return statement

returnStmt := 'return' ( '\n' | expr )

If a newline occurs after "return", that means the function returns none. Otherwise, requires an expression.

While statement

whileStmt := 'while' expr blockStmt