//BNF Rules:

//<> denotes a BNF rule
//"" denotes a keyword which must appear exactly as seen
// | denotes a choice between items
// + denotes additional items for the rule

//EXAMPLES
//ifstatement: if x==3 then y=5;
//type:        float




<program> = <block>

<block> = "{" + <statementlist> + "}" 

<statementlist> = <realstatementlist> | NULL

<realstatementlist> = <statement> + <statementlist>

<statement> = <ifstatement> | <whilestatement> | <printstatement> | <assignstatement> | <declaration> | <block>

<ifstatement> = "if" + <expression> + "then" + <statement> + ";"

<whilestatement> = "while" + <expression> + "do" + <statement> + ";"

<printstatement> = "print" + <expression> + ";" 

<assignstatement> = <identifier> + "=" + <expression> + ";" 

<expression> = <identifier> | <num> | <binaryexpression>

<num>=number

<identifier> = word

<binaryexpression> = "(" + <expression> + <operator> + <expression> + ")"

<operator> = "+" | "-" | "*" | "/" | "=" | "=="

<type> = "int" | "float" | "string"

<declaration> = <type> + <identifier> + ";"