varAssign :: Parser Expr
varAssign = do
    v <- var
    symbol "="
    val <- expr
    return $ assignExpr v val
varAssign :: Parser Expr
varAssign = do
    v <- var
    symbol "="
    val <- expr
    return $ assignExpr v val
varAssign = do
    v <- var
    symbol "="
    val <- expr
    return $ assignExpr v val