if_statement : IF LPAREN cond RPAREN true_statement

def p_if_statement_woelse(self, p):
        'if_statement : IF LPAREN cond RPAREN true_statement'
        p[0] = IfStatement(p[3], p[5], None, lineno=p.lineno(1))
        p.set_lineno(0, p.lineno(1))